"^ 

i 

k 

mil 

tin 


»  »  »  ^  »  »  »  »^'«» 

•9JBD  mjM 

auinjoA  Sim  3[puEi{ 

3SB3[J 


■♦»  »  »"»  »  »   »  »  » 


fmrnm 


Digitized  by  tine  Internet  Archive 

in  2009  with  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/lakebonneville01gilb 


DEPARTMENT  OF  THE  INTERIOR 


MONOGRAPHS 


United  States  Geological  Survey 


VOLUME    I 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 

1890 


U.  8.  GFOLOGICAL  SURVEY 


SHORE-LINES  ON   THE    NORTH  i'  °^  ^^^  OQUIRRH    RANGE,   UTAH. 

.  H.  Holmes. 


VoV 


w 


UNITED  STATES  GEOLOGICAL  SURVEY 

J.  W.  POWELL,  DIRECTOR 


LAKE    BONNEVILLE 


BT 


GROVE  K^RL  GILBERT 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1890 


CONTENTS 


Fage. 

Letter  op  Transmittal  , xv 

Preface xvii 

Abstract  of  Volume xix 

C'liAi'TER  I. — Introduction 1 

Interior  Basins 2 

The  Great  Basin 5 

History  of  Investigation..   12 

Tlie  Bonneville  Basin 2U 

Cbronologic  Nomenchitnro 22 

Chapter  II.— The  ToPOGRArnic  Features  of  Lake  Shores 23 

Wave  Work 2'J 

Littoral  Krosion 29 

The  Sea  Cliff 34 

The  Wave-cut  Terrace 35 

Littoral  Transportat ion 37 

The  Beach , 39 

The  Barrier 40 

The  Subaqueous  Kidgo 43 

Littoral  Deposition 4t) 

Eiu  bankments 46 

The  Spit 47 

The  Bar 48 

The  Hook 52 

The  Loop 55 

The  Wave-built  Terrace 55 

The  V-Torracoand  V-Bar ..    57 

Drifting  Sand  ;  Dunes 59 

The  Distribution  of  Wave-wrought  Shore  Features 60 

Stream  Work;  the  Delta 65 

Ice  Work  ;  the  Rampart 71 

Submergence  and  Emergence 72 

The  Discrimination  of  Sliore  Features  74 

Cliffs 75 

The  Cliff  of  Differential  Degradation 75 

The  Stream  Cliff 75 

The  Coulde  Edge 76 

The  P^ault  Scarp 76 

The  Land-slip  Cliff 77 

Comparison 77 

Terraces 78 

The  Terrace  by  Differential  Degradation 78 

The  Stream  Terrace 79 

The  Moraine  Terrace 81 


VI  CONTENTS. 

Page. 
Chapter  II— The  Topographic  Features  op  Lake  Shores— Continued. 

The  Fault  Terrace 83 

The  Laud-slip  Terrace 83 

Comparison S4 

Ridges 86 

The  Moraine 86 

The  Osar  or  Kame 87 

Comparison 87 

The  Recognition  of  Ancient  Shores 88 

Chapter  III. — Shores  of  Lake  Bonneville 90 

The  Bonneville  Shore-line 93 

The  Question  of  a  Higher  Shore- line 94 

More  Ancient  Lakes 98 

Outline  of  the  Lake 101 

Extent  of  the  Lake 105 

Shore  Details 106 

Embankment  Series Ill 

Determination  of  Still- water  Level 122 

Depth 125 

The  Map    125 

TheProvo  Shore-line 126 

Outline  and  Extent 127 

Shore  Characters 128 

Deltas 129 

The  Underscore 130 

Embankment  Series 131 

The  Map 134 

The  Stansbury  Shore-line 134 

The  Intermediate  Shore-lines 135 

Description  of  Embankments 135 

Grantsville 135 

Preuas  Valley 136 

The  Snow-plow 137 

Stockton  and  Wellsville 137 

Dove  Creek 137 

Comparison  of  Embankments - 137 

Hypothesis  of  Differential  Displacement 140 

Hypothesis  of  Oscillating  Water  Surface 141 

Superposition  of  Embankments 147 

The  Snow-plow 147 

Reservoir  Butte 148 

Stockton , 149 

Blacksmith's  Fork 151 

Dove  Creek 151 

Double  Series  in  Preuss  Valley 152 

Deltas 153 

American  Fork  Delta 155 

Logan  Delta 159 

Summary - ICG 

Tufa 167 

R4sum6 161) 

Chapter  IV.— The  Outlet 171 

Red  Rock  Pass 173 

Mar.sh  Valley 176 

The  River 176 


CONTENTS.  VII 

Page. 
Chaptkr  IV.— The  Outlet — Continued. 

The  Gate  of  Bear  Kiver 178 

The  Question  of  an  Earlier  Discharge 180 

The  Old  River  Bed 181 

Other  Ancient  Rivers 184 

Outlets  and  Shore-lines 186 

Chapter  V. — The  Bonneville  Beds 188 

Lower  River  Bed  Section 189 

Lemington  Section - 192 

Upper  River  Bed  Section 194 

Yellow  Clay 194 

First  Gravel '- 194 

White  Marl 195 

Lower  Sand 195 

Second  Gravel 195 

Upper  Sand 196 

Upper  Gravel 196 

Oscillations  of  Water  Level — 196 

Height  of  the  First  Maximum 199 

The  Whiteness  of  the  White  Marl 200 

Source  of  Material 203 

Composition  of  Lake  Water 204 

Experiments 205 

Deposition  by  Desiccation 208 

Organic  Remains 209 

Joint  Structure 211 

Chapter  VI.— The  History  of  the  Bonneville  Basin 214 

The  Pre-Bonneville  History 214 

Alluvial  Cones  and  Aridity 220 

The  Post-Bonne ville  History 222 

Subdivision  of  the  Basin 222 

Snake  Valley  Salt  Marsh , 223 

Sevier  Lake 224 

Salt  Bed 225 

Rush  Lake 228 

Great  Salt  Lake 230 

Surveys 230 

Depth 230 

Gauging 230 

Oscillations  since  1875 233 

Oscillations  prior  to  1875 239 

Changes  in  area 243 

Causes  of  Change 244 

Future  Changes 250 

Saline  Contents 251 

Sources  of  Saline  Matter 254 

Rate  and  Period  of  Salt  Accumulation 255 

Fauna 258 

The  General  History  of  the  Bonneville  Oscillations 259 

The  Topographic  Interpretation  of  Lake  Oscillations 262 

Hydrographic  Hypothesis 263 

Orogenic  Hypothesis 263 

Epeirogenic  Hypothesis 264 

The  Climatic  Interpretation  of  Lake  Oscillations .  265 

Opinions  on  Correlation  with  Glaciation 265 


VIII  CONTENTS. 

Page. 
Chapter  VI. — The  History  of  the  Bonneville  Basin— Coiitintiod. 

The  Argument  from  Aualogy 2C9 

Recency i!69 

Episodal  Character 269 

Bi  partition 270 

Genetic  Correlation , 275 

The  EtFect  of  a  Change  in  Solar  Energy 283 

The  Evidence  from  Molluscan  Life 297 

Depauperation  and  Cold :{00 

Depauperation  and  Salinity 'Ml 

The  Evidence  from  Vertebrate  Life :50:{ 

The  Evidence  from  Encroaching  Moraines ;;()5 

Wasatch-Bouueville  Moraines 30G 

Siena-Mono  Moraines 311 

Summary  of  Chapter 310 

Chapter  VII. — Lake  Bonneville  and  Volcanic  Eruption 319 

Ice  Spring  Craters  and  Lava  Field 320 

Pavaut  Butte 325 

Tabernacle  Crater  and  Lava  Field 329 

Pleistocene  Winds • 332 

Funiarolo  Butte  and  Lava  Field 332 

Other  Localities  of  Basalt 335 

Pleistocene  Eruptions  Elsewhere 3.36 

Rhyolite 337 

Summary  and  Conclusions 33s 

Chapter  VIII. — Lake  Bonneville  and  Diastrophism 340 

Evidence  from  Faulting;  Fault  Scarps 340 

General  Features  of  Fault  Scarps 354 

Local  Displacements  versus  Local  Loading  and  Unloading 357 

Monutaiu  Growth 359 

Earthquakes 360 

Evidence  from  Shore-lines 362 

Measurements 362 

Deformation  of  the  Bonneville  Shore-liue 365 

Deformation  of  the  Provo  Shore-line 371 

Deformation  during  the  Provo  Epoch 372 

Postulate  as  to  the  Cause  of  Deformation - 373 

Hypothesis  of  Gcoidal  Dcformatiou 376 

Hypothesis  of  Expansion  froui  Warming 377 

Hypothesis  of  Terrestrial  Deformation  by  Loading  and  Unloading 379 

Evidence  from  the  Position  of  Great  Salt  Lake 384 

The  Strength  of  the  Earth 387 

Chapter  IX.— The  Age  of  the  Equus  Fauna 393 

The  Fauna  and  its  Physical  Relations 393 

The  Paleontologic  Evidence 397 

Appendix  A.— Altitudes  and  their  Determination.     By  Albert  L.  Webster 405 

Scheme  of  Tables 405 

Trigonometric  Data 406 

Barometric  Data 406 

Lake  Records 409 

Railroad  Records 411 

Special  Spirit-level  Determinations 411 

Combination  of  Data 413 

Altitudes  of  Shorelines  and  their  Differences 416 


CONTENTS.  IX 


Page. 


Appendix  B. — On  the  Deformation  of  the  Geoid  by  the  Removal,  through  Evapo- 
ration, OF  THE  Water  of  Lake  Honnevili.e.     By  R.  S.  Woodward 4^)1 

Appendix  C— On  the  Elevation  of  the  Surface  of  the  Bonnkvillb  Basin  by  Ex- 
pansion DUB  TO  change  OF  CLIMATE.     By  R.  S.  Woodward 42.') 

Index 407 

TABLES. 

Table  I.  Dimensions  of  Lakes 106 

II.  Enibaukinent  Series  of  the  Bonueviilo  Shore- line 119 

III.  Analyses  of  Bouiievillo  Sediments 201 

IV.  Con<len6ed  Results  of  Analyses  in  Table  III 202 

V.  Mineral  Contents  of  Fresh  Waters  in  the  Salt  Lake  Basin 207 

VI.  Analysis  of  Sevier  Lake  Desiccation-products  and  Brine 227 

VII.  Datum  Points  Connected  with  the  Gau};ing  of  Great  Salt  Lake 2;i:( 

VIII.  Record  of  the  Oscillations  of  Great  Salt  Lake 2:{:i 

IX.  Analyses  of  Water  of  Great  Salt  Lake 203 

X.  Accumulation  Periods  for  Substances  Contained  in  the  Briue  of  Great  Salt  Lake  255 

XI.  Fresh-water  SliellH  in  the  Bonueville-Lahontan  Area 298 

XII.  Measurements  ci(  Fliiminicola  fiisea .'502 

XIII.  Height  of  tbe  Bonneville  Shore  line  at  various  points 306 

XIV.  Height  of  the  Provo  Shore-line  at  various  points 370 

XV.  Diftereuce  in  Altitude  of  the  Bonneville  and  Provo  Shore-lines  at  various  points  372 

XVI.  Comparison  of  post-Boinioville,  post-Provo,  and  Provo  Deformations 374 

XVII.  Summary  of  Paleontolngic  Data  for  the  Determination  of  the  Age  of  the  Equus 

Fauna 400 

XVIII.  Differences  of  Altitude  determined  by  Trigonometric  Observations 406 

XIX.  Ditt'erenoes  of  Altitude  determined  by  Barometric  Observations 408 

XX.  Reduction  of  various  Lake  Gauge  Zeros  to  the  Lake  Shore  Datum' 410 

XXI.  Gauge  Records  showing  tbe  Height  of  the  Water  Surface  of  Great  Salt  Lake      . 

at  various  dates 411 

XXII.  Differences  of  Altitude  derived  from  Railroad  Survey  Records 411 

XXIII.  Difierences  of  Altitude  by  Special  Spirit-level  Determinations 412 

XXIV.  Reduction  of  results  to  a  Comiuon  Datum 413 

XXV.  Comparative  Schedule  of  Altitudes  of  the  Bonneville  Shore-line 417 

XXVI.  Comparative  Schedule  of  Altitudes  of  the  Provo  Shore-line 418 

XXVII.  Comparative  Schedule  of  Altitudes  of  the  Stansbury  Shore  line 418 

XX \' I II.  Ditlercuces  in  Altitude  of  the  Bonneville  and  Provo  Shore-lines 419 

XXIX.  Difierences  in  Altitude  of  the  Provo  and  Stansbury  Shore-lines 419 

XXX.  Values  showing  relative  positions  of  Level  Surface.s  in  a  Lake  Basin 425 


ILLUSTRATIONS. 


Map  of  Lake  Bonneville Folded  in  back  of  cover 

Page. 

Plate  I.  Shore-liues  on  the  north  end  of  the  Oquirrh  Range,  Utah (frontispiece). 

II.  The  Great  Basin  and  its  Lakes — 6 

III.  Routes  of  Travel 18 

IV.  Bar  on  the  shore  of  Lake  Michigan 48 

V.  A  Hook.     Dutch  Point,  Grand  Traverse  Bay,  Lake  Michigan 52 

VI.  Cup  Butte,  a  feature  of  the  Bonneville  Shore-line 54 

VII.  Plats  of  Looped  and  V-shaped  Embankments 58 

VIII.  Map  of  the  East  .Side  of  Preu.ss  Valley 92 

IX.  The  Pass  between  Tooele  and  Rush  Valleys,  Utah 96 

X.  Maji  of  Bay  Bars  of  the  Bouueville  Shore-line  in  Snake  Valley,  Utah 112 

XI.  Profiles  of  Bay  Bars  of  the  Bonneville  Shore-line 116 

XII.  Map  show-in};  the  Preseat  Hydrographic  Divisions  of  the  Bonneville  Basin..  122 

XIII.  Map  of  Lake  Bonneville,  showing  its  extent  at  the  date  of  the  Prove  Shore- 

line   128 

XIV.  Profilesof  the  Provo  Shore-line 132 

XV.  Map  of  the  Shore  Emltanknients  near  Grautsville,  Utah. 134 

XVI.  Map  of  the  North  Group  of  Shore  Embankments  in  Preuss  Valley 136 

XVII.  Map  of  the  Middle  Group  of  Shore  Embankments  in  Preuss  Valley 136 

XVIII.  Map  of  the  South  Group  of  Shore  Embankments  in  Preuss  Valley 136 

XIX.  Map  of  the  Snow-plow 138 

XX.  Map  of  the  Pass  between  Rush  and  Tooele  Valleys,  Utah 138 

XXI.  Map  of  Shore  Bars  and  Terraces,  Welisville,  Utah  ..: 138 

XXII.  Map  of  the  Shore  Terraces  near  Dove  Creek,  Utah 138 

XXIII.  Comparative  Profiles  of  the  Intermediate  Shore-lines 138 

XXIV.  Reservoir  Butte  from  the  cast,  showing  Bonneville  Embankments  and  Ter- 

races  --- 

XXV.  Plat  of  Reservoir  Butte 148 

XXVI.  Map  of  the  Deltas  formed  in  Lake  Bonneville  by  the  Logan  River 160 

XXVII.  The  Ancient  Deltas  of  Logau  River  as  seen  from  the  Temple 162 

XXVIII.  Map  of  the  Outlet  of  Lake  Bonneville  at  Red  Rock  Pass,  Idaho 174 

XXIX.  Red  Rock  Pass,  the  Outlet  of  Lake  Bonneville,  as  seen  from  the  north 176 

XXX.  The  Gate  of  Bear  River,  from  the  east 178 

XXXI.  Map  of  the  Old  River  Bed 182 

XXXII.  Geological  map  of  a  portion  of  the  Old  River  Bed 194 

XXXIII.  Comparative  map  of  Great  Salt  Lake,  compiled  to  show  its  increase  of  Area.  244 

XXXIV.  Climate  Curves 246 

XXXV.  Map  of  a  Volcanic  District  near  Fillmore,  Utah 320 

XXXVI.  View  on  Great  Salt  Lake  Desert,  showing  mountains  half  buried  by  lake 

sediments — 320 

XXXVII.  Ice  Spring  Craters ;  Bird's-eye  View  from  the  west 322 

XI 


148 


XII  ILLUSTRATIONS. 

P»ge. 

Plate  XXXVIII.  Ice  Spring  Craters;  the  Crescent  as  seen  from  the  Miter 322 

XXXIX.  The  Taliornaclc  Crater  ami  Lava  Hed.s,  from  the  north 328 

XL.  Pavant  Uutte  from  llio  south 320 

XLI.  Map  showing  the  Distrihutiou  of  Basalt 334 

XLII.  Map  of  the  Mouths  of  Little  and  Dry  Cottonwood  Canyons,  showing  Glacial 

Moraines  anil  Taults 'MC 

XLIII.  Trough  produced  by  Faulting  near  the  month  of  Little  Cottonwood  Canyon.  34G 

XLIV.  Fault  Scarp  crossing  Alluvial  Cone,  near  Salt  Lake  City 348 

XLV.  Map  showing  Lines  of  recent  Faulting 352 

XLVI.  Deformation  of  the  Honneville  Shore-line 3(i8 

XLVII.  Deformation  of  the  Provo  Sliore-line 372 

XLVIII.  Vertical  Interval  between  the  Bonneville  and  Provo  Shore-lines 372 

XLIX.  Map  showing  tho  Glaciated  Districts  of  the  Binini-vilie  Basin 374 

L.  Theoretic  Curves  of  Post-Bon neville  Deformation   374 

LI.  Map  of  Black  Rock  and  vicinity,  Utah,  showing  the  position  of  the  Black 

Rock  Bench 300 

Fig.   1.  Sheep  Rock,  a  Sea  Clifi' 35 

2.  Section  of  a  Sea  Clitf  and  Cut-Terrace  in  Incoherent  Material 'Mi 

3.  Section  of  a  Sea  Cliff  and  Cut-Terrace  in  Hard  Material 3tl 

4.  Section  of  a  Beach 39 

5.  Section  of  a  Ciit-and-Bnilt  Terrace 40 

6.  Section  of  a  Barrier 40 

7.  Section  of  a  Linear  Embanlvuieut 49 

8.  Map  of  Braddock's  Bay  and  vicinity,  New  York,  showing  Headlands  conijccted  by  Bars.  50 
y.  Map  of  tlie  head  of  Lake  Superior,  showing  Bay  Bars 51 

10.  Diagram  of  Lake  Ontario,  to  show  the  Fitcli  of  Waves  reaching  Toronto  from  different 

directions - 53 

11.  Map  of  tho  Harbor  and  Peninsula  (Hook)  at  Toronto 54 

12.  Section  of  a  Linear  Embaukmcut  retreating  Landward 56 

13.  Section  of  a  Wavobuilt  Terrace 56 

14.  Section  of  a  Delta 68 

15.  Vertical  Section  in  a  Delta,  showing  the  typical  Succession  of  Strata 70 

16.  Section  of  a  Rampart 71 

17.  Ideal  Section,  illustrating  the  formation  of  a  Moraine  Terrace  at  the  side  of  a  Glacier.  82 

18.  Ideal  Section,  showing  the  internal  strnctur(M)f  grouped  Lateral  Moraine  Terraces 82 

19.  Ideal  Section  of  Alluvial  Killing  against  Front  Edge  of  Glacier 82 

20.  Section  of  resulting  Frontal  Mcnaine  'I'errace '83 

21.  Bonneville  and  Internuiliate  Kmliankments  near  Wellsville,  Utah,  showing  contrast 

between  Littoral  and  Subaerial  Topography 98 

22.  Butte  near  Kelton,  Utah 108 

23.  Bars  near  George's  Ranch,  Utah 114 

24.  Limestone  flutte  near  Redding  Spring  ;  an  Island  at  tho  Provo  Stage 129 

25.  Compound  Hook  of  an  Intermediate  Shore-lino  m!;ir  Willow  Spring,  Great  Salt  Lake 

Desert 145 

26.  General  izeil  Section  of  Deltas  at  the  Month  of  American  Fork  Canyon 156 

27.  Partial  Section  of  Deltas  .at  Logan,  Utah 162 

28.  Section  showing  succ(!ssion  of  l.„acustrine  and  Alluvial  Deposits  at  Lemingtou,  Ut.ali.  192 

29.  The  Upper  River  Bed  Section 191 

30.  Diagram  of  Lake  Oscillations,  inferred  from  Deposits  and  Erosions 198 

31.  Sevier  Lake  in  1S72 227 

32.  Annual  Rise  and  Fall  of  tho  Water  Surface  of  Groat  Salt  Lake 239 

33.  Non-periodic  Rise  .and  Fall  of  Great  Salt  l<ako 243 

34.  Rise  and  Fall  of  Water  in  the  Bonneville  Basin 262 

3.5.  First  Diagram  of  Glaciation  Theory 289 


ILLUSTRATIONS.  XIII 

Page. 

Fig.  36.  Second  Diiisiaiu  of  Glacial  ion  Theory 29'.i 

37.  Diagram  to  illustrate  the  Alternation  of  Voloimic  Eruptiou  and  Littoral  Erosion  on 

Pavant  liiitte 327 

38.  Section  of -I'avant  Butte 327 

39.  Section  at  Ha.se  of  I'avant  Unite,  showing  remnant  of  earlier  Tuff  Cone 328 

40.  Theoretic  St^ction  of  Knmarole  Bntte 333 

41.  Uiinderbero;  Butte 335 

42.  Protilesof  the  Rock  Canyon  Delta 344 

43.  Son  til  Half  of  Rock  Canyon  Delta,  showing  Fault  Scarp.s 345 

44.  Profile  of  the  South  Moraine  at  tln^  Mouth  of  Little  Cottonwood  Canyon,  .showing  the 

effect  of  Faulting 347 

45.  Profile  of  Fault  Scarps  near  Big  Cottonwood  Canyon 347 

46.  Shored ines  and  Fault  Scarp  near  Farmington,  Utah 350 

47.  Profile  of  Fanlt  Scarps  near  Ogileu  Canyon,  Utah 350 

48.  Diagram  to  illustrate  theory  of  Grouped  Fault  Scarps  in  Alluvium 355 

49.  Generalized  cross-jirofile  of  mountains  and  valleys,  illustrating  Post-Bon ueville  Dias- 

tropliic  Changes 367 

50.  Diagram  of  Post-Bon neville  Diastrophic  Changes 367 

51.  Cross-.sectiou  of  Ideal  Lenticular  Lake  Basins 423 

KRRATUM  TO  PLATE. 

Plate  XLII.  For  "  Big  Cottonwood  Cr."  read  Dry  Cottonwood  Cr 346 


LETTER  OF  TRANSMITTAL. 


United  States  Geological  Survey, 

Division  of  the  Great  Basin, 
Washington,  D.  C,  June  29,  1889. 
Sir:     I  have  the  honor  to  transmit  herewith  the  manuscript  of  a  final 
report  on  Lake  Bonneville. 

To  yourself,  and  to  the  Hon.  Clarence  King,  under  whose  direction  a 
large  part  of  the  investigation  was  conducted,  I  am  indebted  not  only  for 
the  facilities  which  have  rendered  the  research  possible,  but  also  for  never- 
failing  kindness  and  encouragement,  that  have  added  zest  and  pleasure  to 
the  work. 

Very  respectfully,  your  obedient  servant, 

G.  K.  Gilbert, 

Geologist  in  Charge. 
Hon.  J.  W.  Powell, 

Director  U.  S.  Geological  Survey,  Washington,  D.  C. 


PREFACE. 


When  tlie  Geological  Survey  was  created,  in  1879,  it  had  for  its  field 
of  operations  the  country  west  of  the  Great  Plains.  In  its  original  organi- 
zation, under  the  directorship  of  Clarence  King,  the  Division  of  the  Great 
Basin  was  established,  with  headquarters  at  Salt  Lake  City,  and  the  Divis- 
ion undertook  as  its  first  large  work  the  investigation  of  the  Pleistocene 
lakes. 

Afterward  the  field  of  operations  of  the  Survey  was  extended  over  the 
entire  United  States,  and  as  the  ajjpropriations  of  funds  were  not  corre- 
spondingly increased,  a  re-organization  became  necessary.  One  factor  of 
that  re-organization  was  the  abolition  of  the  Great  Basin  Division.  Its  last 
field  examinations  were  made  in  1883,  and  the  publication  of  the  present 
volmne  closes  its  work. 

The  preparation  of  the  volume  was  begun  before  the  re-organization, 
and  many  of  the  plates  for  its  illustration  were  then  engraved.  It  was 
planned  to  be  chiefly  descriptive  and  to  be  restricted  to  the  single  lake 
whose  name  it  bears.  All  general  discussions  were  to  be  deferred  until 
many  lakes  had  been  studied.  But  when  it  became  necessary  to  bring  the 
work  to  a  close,  the  plan  of  publication  was  changed,  and  it  was  determined 
to  include  in  this  volume  such  generalizations  as  were  permitted  by  the 
material  gathered. 

This  change  of  plan  is  in  part  responsible  for  the  great  delay  in  the  com- 
pletion of  the  manusci-ipt,  but  the  chief  cause  of  delay  has  been  the  assump- 
tion by  myself  of  new  duties  before  old  ones  were  fully  discharged. 

Portions  of  the  material  of  the  volume  have  already  received  publica- 
tion in  various  ways.     An  outline  of  the  history  of  Lake  Bonneville  appeared 

XVII 
MON  I 11 


XVIII  PKEFACE. 

in  the  Second  Annual  Report  of  the  Sm-Ney.  A  ])ai-tial  discussion  of  the 
deformation  of  the  plane  of  tlic  Bonneville  shore-line  was  ])resented  to  tlie 
American  Society  of  Naturalists  at  its  IJoston  meeting,  ISS").  The  Fifth 
Annual  Report  contained  a  paper  on  the  topographic  features  of  lake  shores. 
Tlie  subjects  of  the  first  and  second  of  these  publications  are  here  greatly 
amplified.  The  text  of  the  third  is  in  large  part  repeated  in  the  .second 
chapter  of  this  volume;  but  the  sj)ecialist  will  find  new  matter  on  pages 
25-26,  30-31,  3:i,  42-4"),  nS-fib,  03-65,  71,  <S()-,S3.  He  will  also  note  that 
the  discussion  of  rhythmic  embankments  takes  a  new  form  in  another 
chapter. 

To  those  assistants,  colleagues,  and  fellow  students  who  have  contrib- 
uted to  my  store  of  material  I  have  endeavored  to  give  credit  in  the  pages 
of  the  text,  but  it  has  been  impossible  there  to  acknowdedge  my  multifarious 
obligations  for  friendly  aid,  advice,  and  criticism.  To  numerous  citizens  of 
Utah  and  Nevada  I  am  indebted  for  substantial  favors,  and  some  parts  of 
the  w'ork  would  have  been  very  difficult  ^^'ithout  the  special  facilities  afiVirded 
by  the  railways  of  Utah. 

G.  K.  G. 


ABSTRACT  OF  VOLUME 


Chapter  I:  Introduction. — Diastropliic  processes  tend  to  the  formation  of  closed  liasins;  atmos- 
pheric, to  tlieir  dostriictiou.  In  arid  reijions  formative  processes  jireyai] ;  in  buiiiid,  destruc- 
tive.— The  Great  Basin  is  tlie  chief  North  American  rlistrict  of  interior  drainage,  l)nt  is  inferior 
to  those  of  other  continents.  Its  dry  climate  is  caused  by  certain  relations  of  winds  and  ocean 
cnrrents. — The  Pleistocene  lakes  of  the  Great  Basin  have  been  previously  studied  liy  Stansbnry, 
Beckwith,  Blake,  Simjison,  En';e!niann,  Whitney,  King,  HaKUe,  Emmons,  Maydcn,  Bradley, 
Poole,  Howell,  and  Pcale. — The  Bonneville  Basin  is  the  northeastern  part  of  the  Great  Basin, 
and  includes  one-fourth  its  area. — The  term  Pleistocene  is  preferred  to  Quaternary,  as  being  less 
counotive. 

Chapter  II:  Topographic  Keaturks  ov  Lake  Shores. — The  waves  and  shore  cnrrents  of  lakes  are 
produced  by  the  same  winds.  They  work  together  in  littoral  transportation.  Where  a  shore 
current  is  accelerated,  littoral  erosion  occurs ;  where  it  is  retarded,  littoral  deposition.  Where 
the  current  departs  from  the  shore  a  spit  is  built. — The  delta  formation  has  three  parts.  The 
upper  and  middle  parts  are  coarser  than  the  lower;  the  bedding  of  the  middle  is  more  highly 
inclined  than  that  of  the  upper  and  lower. — An  adolescent  coast  is  marked  by  narrow  terraces 
and  absence  of  shore  drift  and  embankments;  numerous  embankments  mark  the  mature  coast. — 
Wave  work  renders  coast  lines  less  tortuous.— Clift's,  terraces,  and  ridges,  due  to  shore  processes, 
may  be  distinguished  from  si  miliar  features  produced  otherwise  by  the  study  of  their  forms, 
structures,  and  relations. 

Chapter  III:  Shores  of  Lake  Bonneville. — The  Bonneville  shore-line  is  about  1,000  feet  above 
Great  Salt  Lake,  and  compasses  an  area  of  19,7f)0  S(inare  miles.  The  Provo  shore-lino  contours 
the  basin  'MH  feet  lower,  and  is  the  strongest  marked  of  all  the  shore-lines.  Between  the  Bonne- 
ville and  the  Provo  are  the  Intermediate  shore-lines. — The  synchronism  of  the  entire  Bonneville 
shore-line  is  shown  by  its  scries  of  embankments. — The  Intermediate  embanknuiuts  are  ryhthmic 
products  of  the  irregular  oscillations  of  the  water  surface. — Deltas  belong  chielly  to  the  Provo 
shore-line. — Tufas  were  deposited  just  below  the  water  surface. — The  chronologic  order  of  the 
shore-lines  is  (1)  Intermediate,  ('-i)  Bonneville.  (I!)  Provo. 

Chapter  IV  :  Outlet. — At  the  level  of  the  Bonneville  shore-line  the  lak(^  overllowed,  sending  a  stream 
from  the  north  end  of  Cache  Valley  northward  to  tlieSn;ike  River.  The  sill  of  the  outlet  was  of 
alluvium,  but  with  a  limestone  ledge  beneath.  The  alluvium  w:is  easily  washed  away,  and  a 
prism  of  water  about  37.')  feet  deep  went  out  by  a  debacle,  lowering  the  lake  to  the  level  of  the 
limestone  ledge.     This  level  coincides  with  the  Provo  shore-line. 

Chapter  V:  Bonneville  Beds. — Within  the  circle  of  the  Bonneville  shore-line  are  lake  sediments  of 
the  same  date.  The  White  Marl,  relatively  thin  and  calcareous,  lies  above  the  Yellow  Clay,  rela- 
tively thick  and  aluminous. — They  are  separated  by  a  plane  of  erosion,  testifying  to  a  dry  epoch 
between  two  humid  epochs.  The  calcareous  character  of  the  upper  member  is  theoretically  con- 
nected with  the  burial  of  salts  during  the  dry  epoch. — The  strata  contain  fresh-water  shells  of 
living  species. — They  are  divided  by  a  system  of  parallel  joints,  ascribed  to  earthquake  shocks. 

XIX 


XX  ABSTRACT  OF  VOLUME. 

Chapter  VI :  History  of  Bonnkvii.i.f.  Basin. — Previous  to  fho  Bonneville  history  the  basin  was 
.arid.  Tlie  lirst  rise  of  tlio  lake  was  without  overllow,  aurl  was  long  maintained  ;  the  Yellow  Clay 
was  then  depo.sited.  The  Becond  rise  went  ilO  feet  higher,  eansing  overllow,  lint  was  of  shorter 
dnration  ;  tire  White  Marl  was  then  deposited.  The  final  drjinK  divided  the  basin  into  a  dozen 
indi^pendent  basins,  the  largest  of  which  contains  Great  Salt  Lake.  Since  1H4.'>  that  lake  has 
repeatedly  risen  .and  fallen  throngh  a  range  of  10  feet.— The  history  of  Lake  Bonneville  is  par- 
alleled by  that  of  Lake  Lahontan,  and  each  is  connected  willi  a  history  of  glaeiation  in  adjacent 
iniinntains.  This  connection,  the  deiianperatiou  of  the  fossil  shells,  and  an  analysis  of  the  climatic 
conditions  of  glaeiation,  lead  to  the  conclusion  that  the  lacustrine  ejiochs  were  epochs  of  relative 
cold. 

Chaptkr  VII:  Lakr  Boxnkvillkand  Volcanic  Eruption. —The  group  of  small  craters  and  basaltic 
lava  fields  near  Fillmore,  Utah,  are  closely  related  to  the  lake  history.  Somi;  eruptions  took  place 
beneath  the  water  of  the  lake,  others  since  its  disappearance,  and  others  again  during  the  inter- 
lacustrine  epoch. — Numerous  basaltic  ernptions  occurred  in  the  lake  area  before  the  lake  period, 
and  at  still  earlier  dates  rhyolite  was  extra va.sated. 

Cii.M'Tku  VIII:  Lakk  Bonnevii.lk  and  Diastropiiism. — Orogenic  change  during  a  period  subseijueut 
to  the  lake  is  shown  by  fault  scarps.  The  formation  of  fault  scarps  is  accompanicil  by  earlh- 
i|uakes. — Epeirogeuic  change  during  a  period  snbse<iuent  to  the  lake  i.s  shown  by  the  deformatiiui 
of  the  planes  of  {he  shore-lines.  Under  the  postulate  that  the  doming  of  the  planes  is  due  to  the 
drying  away  of  the  lake,  it  is  concluded  that  the  strains  induced  by  the  unloacling  of  the  areas 
exceeded  the  elastic  limit  of  the  material  and  caused  viscous  distortion  of  the  earth's  crust. 
This  result,  taken  in  connection  with  the  phenomena  of  mountain  uplift,  leads  to  an  estimatB  of 
the  strength  of  the  crust. 

Chapter  IX:  Aok  of  the  Equus  Fauxa. — The  Equus  fauna  at  its  type  locality  is  contained  in  lake 
lieds  correlated  by  physical  relations  with  the  up|)erinost  of  the  Lahontan  and  Bonneville  beds, 
The  fauna,  previously  called  later  Pliocene,  is  thus  shown  to  have  lived  in  late  Pleistocene  time. 


LAKE    BONNEVILLE, 


BY  G.   K.  GILBERT. 
CHAPTER     I. 

INTRODUCTION. 


This  volume  is  a  contribution  to  the  hiter  physical  history  of  the  Great 
Basin.  As  a  geographic  province  the  Great  Basin  is  characterized  by  a  dry 
climate,  by  interior  drainage,  and  by  a  peculiar  mountain  system.  Its  later 
history  includes  changes  of  climate,  changes  of  drainage,  volcanic  eruption, 
and  crustal  displacement.  Lake  Bonneville,  the  special  theme  of  the  vol- 
ume, was  a  phenomenon  of  climate  and  drainage,  but  its  complete  history 
includes  an  account  of  contemporaneous  eruption  and  displacement. 

When  the  work  of  the  geologist  is  finished  and  his  final  comprehensive 
report  A\ritten,  the  longest  and  most  important  chapter  will  be  ujion  the 
latest  and  shortest  of  the  geologic  periods.  The  chapter  will  be  longest 
because  the  exceptional  fullness  of  the  record  of  the  latest  period  will  enable 
him  to  set  forth  most  completely  its  complex  history.  The  changes  of  each 
period — its  erosion,  its  sedimentation,  and  its  metamorphism — obliterate 
part  of  the  records  of  its  predecessor  and  of  all  earlier  periods,  so  that  the 
order  of  our  knowledge  of  them  must  continue  to  be,  as  it  now  is,  the 
inverse  order  of  their  antiquity. 

The  great  importance  of  the  chapter  on  the  latest  period  lies  in  the 
fact  that  it  will  contain  the  key  for  the  decipherment  of  the  records  of  the 
earlier.     The  records  of  those  periods  consist  of  the  products  of  various 

MON  I 1  1 


2  LAKE  BONNEVILLE. 

processes  of  change,  and  these  products  are  to  be  intei-preted  only  through 
a  knowledge  of  the  processes  themselves.  Many  of  the  j)rocesses  can  l)e 
directly  observed  at  the  pi-eseiit  time,  and  it  is  by  such  observation,  com- 
bined with  the  study  of  freshly  formed  and  perfectly  pi-eserved  pnnhicts, 
that  the  relation  of  product  to  process  is  learned.  It  is  through  the  study 
of  the  phenomena  <^if  the  latest  period  that  the  connection  between  present 
processes  of  change  and  the  products  of  ])ast  changes  is  established. 

In  view  of  these  considerations  the  lionneville  study  has  been  con- 
ducted with  a  double  object,  the  discovery  of  the  local  Pleistocene  history 
and  the  discovery  of  the  processes  by  which  the  changes  constituting  this 
history  were  wrought. 

INTERIOR    BASINS. 

In  physical  geography  the  terms  "basin"  and  "drainage  district"  are 
synonymous,  and  are  used  to  indicate  any  area  which  is  a  unit  as  to  drain- 
age. The  basin  of  a  stream  is  the  tract  of  C(iuntr\-  it  drains,  whether  the 
stream  is  a  great  river  or  the  most  insignificant  triljutary  to  a  river.  We 
thus  speak  of  the  basin  of  the  Ohio  and  of  the  Ijasin  of  the  Mississippi,  and 
say  that  the  latter  includes  the  former.  And  it  may  be  said  in  general  that 
the  basin  of  any  branching  stream  includes  the  basins  of  all  its  tributaries. 

The  l)asin  of  a  lake  is  the  tract  of  country  of  which  it  receives  the 
drainage,  and  it  includes  not  only  the  basins  of  all  affluent  streams  ])ut  the 
area  of  the  lake  itself  The  term  "lake  basin"  is  also  aj)plied  to  the  depres- 
sion occupied  by  the  water  of  a  lake  and  limited  l)y  its  .shores,  and  where 
confusion  might  arise  from  the  double  use,  the  wider  sens-i  is  usually  indi- 
cated by  the  adjective  "hydrographic"  or  its  equivalent.  If  the  lake  has 
an  outlet  its  basin  is  a  part  of  the  basin  of  the  effluent  stream,  but  if  it  has 
no  outlet  its  basin  is  complete  in  itself,  and  is  Avholly  encu'cled  by  a  line  of 
water-parting.  In  such  case  it  is  called  a  co>ifi)i(')/f(il,  or  i)!f('rio>;  or  eJoscfl, 
or  shut,  or  drainless  basin. 

If  an  interior  basin  exists  in  a  climate  so  arid  that  the  superficial  ffow 
of  water,  which  constitutes  drainage,  is  only  potential  and  not  actual,  or 
else  is  occasional  only  and  not  continuous,  it  contains  no  })erennial  lak-'^ 
and  is  called  a  dry  basin. 


INTERIOR  BASINS.  3 

The  boundaries  separating  basins  are  water-partings  or  divides,  and 
these  are  of  all  characters,  from  the  acute  crests  of  mountain  ranges  to  low 
rolls  of  the  plain  scarcely  discernible  by  the  eye.  Interior  basins  are  com- 
])letelY  encncled  by  lines  of  water-parting. 

The  existence  of  interior  Ijasins  depends  on  two  conditions:  a  suitable 
topographic  configuration  and  a  suitable  climate.  The  ordinar}^  process  of 
land  sculpture  by  running  water  does  not  produce  cup-like  basins,  but  tends 
on  the  contrary  to  abolish  them.  Wherever  a  topographic  cup  exists  the 
streams  flowing  toward  it  deposit  within  it  their  loads  of  detritus,  and  if 
they  are  antagonized  by  no  other  agent  eventually  till  it.  If  the  cup  con- 
tains a  lake  with  outlet  the  outflowing  stream  erodes  the  rim  of  the  basin, 
and  eventually  the  lake  is  completely  drained. 

The  work  of  streams  occasionally  produces  topographic  cups  by  the 
rapid  formation  of  alluvial  deposits  where  two  streams  meet.  If  the  power 
of  one  stream  to  deposit  is  greatly  increased,  or  if  the  power  of  the  other 
stream  to  erode  is  greatly  diminished,  the  one  may  build  a  dam  athwart  the 
course  of  the  other  and  thus  produce  a  lake  basin. 

The  great  agent  in  the  production  of  lake  basins,  or  the  agent  which 
has  produced  most  of  the  large  basins,  is  diastrophism,^  and  in  a  majority 
of  the  cases  in  which  basins  are  partitioned  off  by  the  alluvial  process  just 
described,  the  change  in  the  relative  power  of  the  streams  is  brought  about 
by  diastrophism. 

Other  basin-forming  agencies  are  volcanic  eruption,  limestone  sinks, 
wind  waves,  dunes,  land  slides  and  glaciers.  By  far  the  greatest  number 
of  topographic  cups  are  due  to  glaciers;  but  with  these  we  are  not  now 
concerned. 

The  basins  of  ordinary  lakes  are  distinguished  from  interior  basins  by 
overflow,  and  that  depends  on  climate.  The  rainfall  of  each  basin  is  or 
may  be  disposed  of  by  three  processes:  first,  evaporation  from  tlie  soil  and 

'I  finil  it  advantageous  to  follow  J.  W.  Powell  in  the  use  of  diastrophism  as  a  general  term  for 
the  process  or  processes  of  deformation  of  the  earth's  crust.  The  products  of  diastrophism  are  conti- 
nents, plateaus  and  mountains,  ocean  beds  and  valleys,  faults  and  folds.  Diastrophism  is  coordinate 
with  voleanism,  and  is  the  synonym  of  displacement  and  dislocation  in  the  more  general  of  the  two 
geologic  meanings  accjuired  by  each  of  those  words.     Its  adjective  is  diastropldc. 

It  is  convenient  also  to  divide  diastrophism  into  orogeny  (monntaiu-making)  .and  epeirogeny 
(continent -making).  The  words  epeirogeny  and  epeirogenic  are  defined  iu  the  opening  paragraph  of 
chapter  VIII. 


4  LAKE  BONNEVILLE. 

from  the  vegetation  supported  by  it;  second,  evaporation  from  a  lake  sur- 
face; third,  outflow.  If  the  rainfall  is  sufficiently  small,  it  is  all  retiu'ned 
to  the  air  l)y  evaporation  from  the  s<iil  and  vegetation,  and  the  Itasin  is  dry. 
If  it  is  somewhat  larger,  the  portion  not  directly  evaporated  Jiccumidiitcs  in 
the  lowest  depression,  forming  a  lake,  from  the  surface  of  which  evaporation 
is  more  rapid.  The  area  of  the  lake  surface  is  determined  by  the  area  of 
the  basin,  the  rainfall  and  the  local  rates  of  evaporation.  The  basin  is 
closed  so  long  as  a  lake  sufficient  for  the  purpose  of  evaporation  does  not 
require  such  an  extent  as  to  cause  it  to  discharge  at  the  lowest  point  of  the 
rim.  The  area  enclosed  by  a  contour  passing  through  the  lowest  point 
of  the  rim,  the  total  area  of  the  basin,  and  the  local  climate  are  tlie  tln-ee 
factors  which  determine  whether  a  given  topogra})hic  cu])  sliall  constitute 
an  interior  basin.  If  the  ai-ea  of  a  topographic  cup  and  the  area  of  the 
maximum  lake  it  can  contain  are  nearly  identical,  it  may  constitute  an  in- 
terior basin  in  a  region  of  humid  climate.  If  the  contom-  through  the  lowest 
point  of  the  rim  encloses  an  area  very  small  in  comparison  with  the  entire 
basin,  the  maintenance  of  an  outlet  is  not  inconsistent  with  an  arid  climate. 
If  there  were  no  erosion  and  sedimentation,  unchecked  upheaval  and 
subsidence  w^ould  greatly  multiply  the  number  of  basins,  (^n  the  contrary, 
if  all  displacement  should  cease,  and  the  foundations  of  the  earth  become 
stable,  erosion  and  sedimentation  would  merge  all  Ijasins  into  one.  The 
actual  state  of  the  earth's  surface  is  therefore  at  once  the  result  and  the 
index  of  the  continuous  conflict  Itetween  subterranean  forces  on  the  one 
hand  and  atmospheric  on  the  othei".  The  two  processes  which  destroy  ba- 
sins are  conditioned  by  climate.  In  an  arid  basin  the  in  washing  of  detritus 
is  slow  and  there  is  no  outflow  to  corrade  the  rim;  but  with  abundant  rain- 
fall the  accumulation  of  detritus  is  rapid  and  corrasion  cons])ires  Avith  it  to 
diminish  the  inequality  between  center  and  rim.  In  arid  regions,  tlierefore, 
the  formative  subterranean  forces  are  usually  victorious  in  their  conflict  with 
the  destructive  atmos})heric  forces,  and  as  a  result  closed  basins  abound; 
in  humid  regions  the  destructive  agencies  prevail  and  lake  basins  are  rare. 
In  the  present  geologic  age  it  is  necessarv  to  restrict  this  generalization  to 
lands  in  the  lower  latitudes,  because  the  glaciation  of  the  last  geologic  period 
created  an  immense  number  of  lake  basins  in  humid  regions  of  high  latitude, 
and  running  water  has  as  yet  made  little  pn)gress  in  their  destruction. 


TOPOGRAPHY  OF  THE  GREAT  BASIN.  5 

THE     GREAT     BASIN. 

The  major  part  of  the  North  Amei'ican  continent  is  drained  by  streams 
flowing-  to  the  ocean,  but  there  are  a  few  restricted  areas  having  no  out- 
ward drainage.  The  hxrgest  of  the.se  was  called  by  Fremont,  who  first 
achieved  an  adequate  conception  of  its  character  and  extent,  the  "Great 
Basin,"  and  is  still  universally  known  by  that  name.  It  Is  not,  as  tlu;  title 
might  suggest,  a  single  cup-shaped  depression  gathering  its  waters  at  a  com- 
mon center,  but  a  broad  area  of  varied  surface,  naturally  divided  into  a 
large  numljer  of  independent  drainage  districts.  It  lies  near  the  Avestern 
margin  of  the  continent  and  is  embraced  l)y  rivers  trll^utary  to  the  Pacific 
Ocean.  On  the  north  it  Is  Ijounded  by  the  drainage  basin  of  the  Columbia, 
on  the  east  by  that  of  the  Colorado  of  the  West,  and  on  the  west  by  the 
basins  of  the  San  Joaquin,  the  Sacramento,  and  numerous  minor  streams. 
The  central  portion  of  the  western  water-parting  is  the  crest  of  the  Sierra 
Nevada,  one  of  the  greatest  mountain  masses  of  the  United  States,  and  far- 
ther south  high  moimtains  constitute  much  of  the  boundary.  The  northern 
half  of  the  eastern  boundary  is  likewise  high,  winding  through  the  region 
of  the  High  Plateaus.  The  remainder  of  the  boundary  does  not  follow  any 
continuous  Hue  of  upland,  but  crosses  mountain  ranges  and  the  intervening 
valleys  without  being  itself  marked  by  any  conspicuous  elevations.  It  is 
defined  onlv  through  a  study  of  the  drainage.  The  general  form  of  the 
area,  as  exhibited  on  Plate  II,  is  rudely  triangular,  with  the  most  acute  angle 
southward.  The  extreme  length  in  a  direction  somewhat  west  of  north  and 
east  of  south  is  about  880  miles,  the  extreme  breadth  from  east  to  west,  in 
latitude  40°  30',  is  572  miles,  and  the  total  area  is  approximately  210,000 
square  miles.  Of  political  divisions  it  includes  nearly  the  whole  of  Nevada, 
the  western  half  of  Utah,  a  strip  along  the  eastern  border  of  California  and 
a  large  area  in  the  southern  part  of  the  State,  another  large  area  in  south- 
eastern Oregon,  and  smaller  portions  of  southeastern  Idaho  and  soiithwest- 
ern  Wyoming.  The  southern  apex  extends  into  the  territory  of  Mexico  at 
the  head  of  the  peninsula  of  Lower  California. 

The  region  is  occupied  by  a  number  of  mountain  ridges  which  betray 
system  by  their  parallelism  and  by  their  agreement  in  a  peculiar  structure. 


6  LAKE  BONNEVILLE. 

Their  general  trend  is  northerly,  inclining  eastwiird  in  the  northern  p;irt  of 
the  basin  and  westward  at  the  south.  The  individual  ridges  are  usually 
not  of  great  length,  and  tliey  are  so  disposed  en  eclielon  that  the  traveler 
winding  among  them  may  traverse  the  Ijasin  troni  cjist  to  west  without 
crossing  a  mountain  pass.  The  type  of  structure  is  tliat  (if  the  faulted  mono- 
cline, in  which  the  mountain  ridge  is  produced  l)y  the  uptilting  of  an  oro- 
genic  block  from  one  side  of  a  line  of  fracture,  and  it  has  been  named  (from 
the  region)  the  Basin  Range  ty})e.  Its  distribution,  however,  does  not  coin- 
cide perfectly  with  the  district  of  interior  drainage.  On  the  one  hand  the 
Great  Basin  includes  along  its  eastern  margin  a  portion  of  the  Plateau 
province,  with  its  peculiar  structural  type,  and  on  the  other  the  Basin  Range 
province  extends  southward  through  Arizona  to  New  Mexico  and  Mexico. 

Between  the  ranges  are  smooth  valleys,  whose  alluvial  slopes  and  floors 
are  built  of  the  debris  washed  through  many  ages  from  the  mountains.  In 
general  they  are  trough-like,  but  in  places  they  coalesce  and  assume  the 
character  of  plains.  The  plains  occupy  in  general  the  less  elevated  regions, 
where  an  exceptional  amount  of  detritus  has  been  accmnulated.  In  the  local 
terminology  they  are  called  deserts.  The  largest  are  the  Great  Salt  Lake 
and  Carson  deserts  at  the  north  and  the  Mojave  and  Colorado  deserts  at  the 
south.  The  Escalante,  the  Sevier,  the  Amargosa,  and  the  Ralston  are  of 
subordinate  importance. 

Where  the  basin  is  broadest,  the  general  elevation  of  its  lowlands  is 
about  5,000  feet,  but  they  are  somewhat  higher  midway  between  the  eastern 
and  western  margins,  so  as  to  separate  two  areas  of  relative  depression,  the 
eastern  marked  by  the  Great  Salt  Lake  and  Se\'ier  deserts,  and  the  Avestern 
by  the  Carson  desert.  Southward  there  is  a  gradual  and  irregular  descent 
to  about  sea-level,  and  limited  areas  in  Death  Valley  and  Coahuila  Vallev  lie 
lower  than  the  surface  of  the  ocean. 

The  aridity  of  the  region  is  shown  instrumentally  l»y  tlie  records  of 
rainfjill  and  atmospheric  humidity.  On  the  broad  plain  bounded  east  and 
west  by  the  Appalachian  Mountains  and  the  Mississi}}pi  River,  43  inches  of 
of  rain  falls  in  a  year.  On  the  lowlands  of  the  Great  Basin  there  falls  Init  7 
inches.  In  the  fonner  region  the  average  moisture  content  of  the  air  is  69 
per  cent  of  that  necessary  for  saturation;    in  the  lowlands  of  the  Great 


U  S.GFOLOGICAL   SURVBr 


LAKJS  BONNEVILLE      PL.  K 


Julius  Bicn  it  Co.  lith 


THE    GREAT   BASIN    .\ND    ITS    LAKES 


CLIMATE  OF  THE  GREAT  BASIN.  7 

Basin  it  is  45  per  ceiit.^  From  the  surface  of  Lake  Micliigan  evaporation  re- 
moves each  year  a  layer  of  water  22  inches  deep.^  The  writer  lias  estimated 
that  80  inches  are  yearly  thus  removed  from  Great  Salt  Lake,^  and  Mr. 
Thomas  Russell  has  computed  from  annual  means  of  temperature,  vapor 
tension,  and  wind  velocity  that  in  the  lowhuids  of  the  Great  Basin  the  an- 
nual rate  of  evaporation  from  water  surfaces  ranges  from  GO  inches  at  the 
north  to  150  inches  at  the  south.^ 

The  variation  with  latitude  exhibited  by  the  evaporation  is  found  also, 
inversely,  in  the  rainfall,  but  is  not  clearly  apparent  in  the  humidity.  In 
the  southern  third  of  the  Basin  the  lo'\\land  rainfall  ranges  from  2  to  5  inches. 
On  the  line  of  the  Central  Pacific  Railroad,  between  the  40th  and  42d  par- 
allels, it  averages  7  inches;  in  the  Oregonian  arm  at  the  north,  15  inches. 
The  average  lowland  precipitation  for  the  whole  area  is  between  6  and  7 
inches.  With  the  relative  humidity  approximately  constant,  the  evapora- 
tion rate  varies  directly  and  the  rainfall  inversely  with  the  temperature,  and 
both  latitude  and  altitude  here  make  the  lowland  temperature  fall  toward 
the  north.  The  sympathy  of  rainfall  with  temperature  is  likewise  shown  in 
the  greater  precipitation  of  the  mountains  as  compai-ed  with  adjacent  valleys. 
Mountain  stations  proper  are  wanting,  but  rain-gauge  records  on  the  flanks 
and  in  the  passes  of  mountains  shoAV  a  marked  ad^s-antage  over  those  in 
neighboring  lowlands.  An  estimate  based  on  these,  on  the  records  at  high 
points  in  the  Sierra  Nevada,  and  on  approximate  knowledge  of  the  heights 
and  areas  of  the  mountains  and  plateaus  of  the  Great  Basin,  places  the 
average  precipitation  for  the  whole  district  at  10  inches. 

The  story  of  climate  is  more  eloquently  told  by  the  hydrography  and 
the  vegetation.  In  the  valleys  of  the  northwestern  ann  of  the  basin  there 
are  numerous  lakes,  drainless  and  of  varying  extent,  but  fed  by  streams 
from  mountain  ranges  of  moderate  size.  In  the  middle  region  the  only  per- 
ennial lakes  are  associated  with  mountain  masses  of  the  first  rank.     The 

'Those  figures  aud  those  in  the  preceding  sentences  are  based  ou  data  compiled  hy  the  U.  S.  Sig- 
nal Service.  TInongh  the  courtesy  of  Gen.  A.  W.  Greely,  Chief  Signal  Officer,  the  writer  has  had 
access  to  manuscript  data  as  well  as  printed. 

■=D.  Fiirrand  Henry,  in  a  report  ou  the  meteorology  of  the  Laurentiau  lakes.  Kept,  of  Chief  of 
Engineers  for  the  year  18G8.     Washington,  1800,  p.  980. 

'Report  on  the  lands  of  the  Arid  Regiou  .  .  .  ,  J.  W.  Powell,  2d  ed.,  Washington,  1879,  p.  73. 

*MS.  report  to  the  Chief  Sigual  Officer. 


8  LAKE  BONNEVILLE. 

great  Sierra  forming  the  western  wall  of  the  basin  receives  each  winter  a 
heavy  coating  of  snow — the  greater  ])art  on  the  side  of  the  great  Califoniian 
valley,  but  enough  east  of  the  water-parting  to  maintain  a  line  of  lakes  in 
the  marginal  valleys  of  the  Great  Basin.  The  Wasatch  range  and  its  asso- 
ciated plateaus,  overlooking  the  Basin  from  the  east,  are  less  favored  than 
the  Sierra,  but  still  receive  an  important  precipitation,  and  by  gathering  the 
drainage  from  a  lai'ge  area,  support  Great  Salt  Lake,  the  largest  of  the  Ba- 
sin's water  .sheets.  The  East  Humboldt  Range,  standing  raidwav,  and  one 
of  the  largest  mountain  masses  within  the  basin  area,  catches  enough  moist- 
ure to  feed  at  one  base  two  small  lakes  and  at  the  other  the  Hundjoldt 
River.  The  neighboring  and  smaller  mountains  are  whitened  every  winter 
by  snow,  a  large  share  of  which  either  evaporates  ^\itliout  melting  or,  if 
melted,  is  al)sorbed  by  the  soil,  to  be  returned  to  the  thirsty  air  without 
gathering  in  drainage  ways.  Many  of  them  are  Avithout  perennial  streams; 
some  even  lack  springs;  and  of  the  mountain  creeks,  few  are  strong  enough 
to  reach  the  valleys  before  succumbing  to  the  ravenous  desert  air.  The 
Hmnboldt  itself,  though  fairly  entitled  to  the  name  of  river,  dwindles  as  it 
goes,  so  that  its  remnant  after  a  course  of  two  hunch'ed  miles  is  able  to  sus- 
tain an  evaporation  lake  barely  twenty-five  square  miles  in  extent.  Most 
of  the  small  closed  basins  are  without  ])ermaneut  creek  or  lake,  containing 
at  the  lowest  point  a  playa  or  "alkali  flat" — a  bare,  level  floor  of  fine  saline 
earth,  or  perhaps  of  salt,  over  which  a  few  inches  of  water  gather  in  time 
of  storm. 

In  the  southern  half  of  the  Basin  there  are  no  lakes  dependent  for  their 
water  on  the  interior  ranges.  At  the  east  the  most  southerly  lake  is  Sevier, 
in  latitude  3!)°;  the  last  of  the  lakes  sustained  by  the  Sierra  is  Owens,  be- 
tween the  Sfitli  and  37th  parallels.  Then  for  three  hundred  miles  evapora- 
tion is  supreme.  Playas  abound,  streams  are  almost  unknown,  and  springs 
are  rare.  Death  Vallev,  with  its  floor  of  salt  spread  lower  than  the  surtace 
of  the  ocean,  is  overlooked  on  either  side  by  mountains  from  .5, 000  to  10,000 
feet  high,  but  they  yield  it  no  flowing  .stream,  and  more  than  one  traveler 
has  perished  from  thirst  while  endeavoring  to  pass  from  spring  to  spring. 
The  Mohave  "river"  is  a  hundred  miles  long,  but  it  preserves  its  life  oidy 
by  concealment,  creeping  through  the  gravel  of  the  desert  and  betraying 


CLOUD-BURST  CHANNELS.  9 

its  existence  only  where  ledj^-es  of  rock  athwart  its  conrse  force  it  to  tlie 
surface. 

As  in  other  desert  regions,  precipitation  here  resuhs  only  from  cyclonic 
disturbance,  either  broad  or  local,  is  extremely  irregular,  and  is  often  vio- 
lent. Sooner  or  later  the  "cloud-burst"  visits  eveiy  tract,  and  when  it  comes 
the  local  drainage-way  discharges  in  a  few  hours  more  water  than  is  yielded 
to  it  by  the  ordinary  precipitation  of  many  years.  The  deluge  scours  out 
a  channel  which  is  far  too  deep  and  l)road  for  ordinary  needs  and  which 
centuries  may  not  suffice  to  efface.  The  al)undance  of  these  trenches,  in 
various  stages  of  obliteration,  but  all  manifestly  nnsuited  to  the  every-day 
conditions  of  the  country,  has  naturally  led  many  to  believe  that  an  age  of 
excessive  rainfall  has  but  just  ceased — an  opinion  not  rarely  advanced  by 
travelers  in  other  arid  regions.  So  far  as  may  be  judged  from  the  size  of 
the  channels  draining  small  catchment  basins,  the  rare,  brief,  paroxysmal 
precipitation  of  the  desert  is  at  least  equal  while  it  lasts  to  the  rainfall  of  the 
fertile  plain. 

A  line  of  cottonwoods  marks  the  course  of  each  living  stream,  but 
otherwise  the  lowlands  are  treeless.  So  are  most  of  the  alluvial  foot-slopes 
and  some  of  the  smaller  mountains,  especially  at  the  south.  Except  on  the 
high  plateaus  in  central  Utah,  there  is  little  that  may  be  called  forest.  The 
greater  mountains  have  much  timber  in  their  recesses,  but  are  not  clothed 
with  trees.  The  growth  is  so  irregular  and  interrupted  that  the  idea  of  a 
tree  limit  could  not  have  originated  here,  but  it  may  be  said  tli:it  only  tlie 
straggling  l)ush-like  cedar  passes  below  6,000  feet  at  the  noi'th  or  7,000  feet 
at  the  south.  Only  conifers  are  of  such  size  and  abundance  as  to  have 
economic  importance.  Oak  and  maple  grow  commonly  as  bushes,  forming- 
low  thickets,  but  occasionally  rank  as  small  trees,  along  with  the  rarer  box- 
elder,  ash,  locust,  and  hackberry.  The  characteristic  covering  of  the  low- 
lands is  a  sparse  growth  of  low  bushes,  between  which  the  earth  is  bare, 
excepting  scattered  tufts  of  grass.  Toward  the  north,  and  especially  on  the 
higher  plains,  the  grass  is  naturally  more  abundant  and  the  bushes  occupy 
less  space,  but  the  introduction  of  domestic  herds  favors  the  ascendency  of 
the  bushes.  At  the  south  the  bushes  are  partly  of  different  species,  and  they 
are  partially  replaced  by  cactuses  and  other  thorny  plants.     The  })layas  are 


10  LAKE  BONNEVILLE. 

bare  of  all  vegetation  and  are  usually  luai'giued  by  a  gi-owtli  of  salt-loving 
shrubs  and  grasses.  A  single  southern  bush  bears  leaves  of  deep  green,  but 
with  this  exception  the  desert  plants  are  grey,  like  the  desert  soil.  These, 
and  the  persistent  haze  whose  grey  veil  deadens  all  the  landscape,  weary 
the  eye  with  their  monotony,  so  that  the  vivid  green  marking  the  distant 
spring  is  welcome  for  its  own  sake  as  well  as  for  the  promise  of  refreshment 
to  the  thirsty  traveler. 

-The  causes  of  this  arid  climate  lie  in  the  general  cii'culntion  of  the 
atmosphere,  in  the  currents  of  the  Pacific  Ocean,  and  in  tlie  contiguration 
of  the  land.  There  is  a  slow  aerial  di-ift  from  west  to  east,  so  that  the  air 
coming  to  the  Basin  has  previously  traversed  a  portion  of  the  Pacific,  to 
which  its  temperature  and  humidity  have  become  iidjusted.  Off  the  west 
coast  of  the  United  States  there  is  a  southward  current,  believed  to  be  the 
chief  branch  of  the  Kuro  Siwa.  Prof.  George  Davidson'  estimates  its  width 
at  about  300  miles,  and  finds  that  its  temperature  rises  with  southward 
advance  only  one  degree  Fahrenheit  for  each  degree  of  latitude.  Being 
derived  from  a  north-moving  current,  it  reaches  our  coast  with  a  tempera- 
ture higher  than  that  normal  to  the  latitude,  while  at  the  south  its  tempera- 
ture is  below  the  normal.  As  pointed  out  by  Button,^  the  air  passing  from 
it  to  the  land  at  the  north  is  cooled  by  the  land  and  precijiitates  moisture, 
while  the  similar  air-current  at  the  south  is  warmed  by  the  land  and  con- 
verted to  a  drying  wind.  The  Great  Basin  fulls  within  the  influence  of  the 
drying  wind,  its  southern  ])nrt  being  more  affected  than  its  northern.  At  the 
extreme  south  and  the  extreme  north  the  moinitains  between  the  ocean  and 
the  Basin  do  not  greatly  interfere  with  the  eastward  flow  of  air,  but  between 
latitudes  35°  and  41°  the  Sierra  Nevada  forms  a  continuous  wall,  rarely  less 
than  ten  thousand  feet  high.  In  rising  to  pass  this  obstriu-tion  the  air  loses 
much  of  its  stored  moisture,  especially  in  winter,  and  it  descends  to  the  Basin 
with  diminished  humidity.  The  Basin  is  further  influenced  by  deviations  of 
the  air-currents  from  the  eastward  direction,  and  its  southern  ])art  falls  in 
summer  within  the  zone  of  calms  theoretically  due  to  a  descending  current 
at  the  margin  of  the  northern  trade-wind;  l)ut  observational  data  are  too 
meager  for  the  discussion  of  these  factors. 

1  Letter  to  the  writer. 

'Cause  of  the  Arid  Climate  of  the  western  portion  of  the  U.  S.,  C.apt.  C.  E.  Diitton :    Am.  Jonr. 
Sci.,  3(1  sor.,  vol.  2»,  p.  2-19. 


OTHER  INTERIOR  BASINS.  ,        11 

The  soutliem  portions  of  Arizouu  and  New  Mexico  and  the  western  part 
of  Texas  resemble  the  Great  Basin  in  climate,  and  they  contain  a  number 
of  small  interior  basins.  These  are  not  so  fully  determined  in  extent  as  the 
Great  Basin,  but  several  of  tlit^ni  ma}-  be  approximately  indicated.  One  of 
the  largest  lies  between  the  Rio  Grande  and  its  eastern  branch,  the  Pecos, 
extending-  from  latitude  35°  in  central  New  Mexico  to  latitude  31°  in  west- 
ern Texas.  In  its  broadest  part  it  is  bounded  on  the  west  by  the  San  An- 
dreas and  Orgaii  Mountains,  and  on  the  east  by  the  Sacramento  and  Guada- 
loupe.  Its  area,  of  which  two-thirds  lies  in  New  Mexico,  is  about  12,600 
square  miles.  Southwest  of  the  Rio  Grande,  in  Mexico,  there  is  a  lai-ger 
tract  of  interior  drainage,  containing  a  number  of  saline  lakes,  and  to  one 
of  these.  Lake  Guzman,  the  valley  of  the  Mimbres  River  of  New  Mexico 
descends.  Other  basins  adjacent  on  either  side  to  that  of  the  Mimbres  are 
believed  to  bear  the  same  relati(  m  to  Lake  Guzman,  sloping  gently  toward 
it,  but  contributing  no  Avater  unless  during  periods  of  rare  and  exceptional 
storm.  Yet  other  basins  without  exterior  drainage  are  contiguous  to  these, 
and  unite  to  form  in  soutluA'cstern  New  Mexico  an  arm  of  the  Mexican 
district  of  interior  drainage,  the  area  within  New  Mexico  probably  falling 
between  7,000  and  7,500  square  miles.  North  of  this,  and  intersected  cen- 
trally by  the  103d  meridian  and  the  34th  parallel,  lies  a  smaller  basin,  includ- 
ing the  plain  of  San  Augustin.  Its  area  is  about  1,800  square  miles.  In 
southeastern  Arizona  a  slightly  smaller  basin  lies  between  the  Caliyuro  and 
Dragoon  Mountains  on  the  west  and  the  Pinaleflo  and  Chiricahua  Mount- 
ains on  the  east,  including  the  Playa  de  los  Pimas.  Another  and  still  smaller 
basin  is  known  to  exist  in  tlie  Hualapi  Valley  of  northwestern  Arizona,  anc 
it  is  probable  that  others  occur  in  the  western  part  of  the  Territory,  both 
north  and  south  of  the  Gila  River.  When  all  have  been  deteriuined  and 
measured,  it  is  estimated  that  the  total  area  of  the  interior  basins  of  the  United 
States,  additional  to  the  Great  Basin,  will  be  found  equal  to  25,000  square 
miles,  making  the  grand  total  for  the  United  States  about  232,000  square 
miles — the  thirteenth  part  of  our  territory.  Mexico  contains  other  inland 
districts  besides  the  one  mentioned  above,  and  the  total  area  in  that  country 
may  be  one-third  as  great  as  ours.  It  is  probable  that  the  remainder  of  the 
continent  di-ains  to  the  ocean. 


12  LAKE  BONNEVILLE. 

Large  as  are  these  districts,  it  is  nevertheless  true  that  North  America, 
as  compared  Avith  otlier  continents,  is  not  characterized  by  interior  (h-ainage. 
According  to  data  compiled  by  Murra}-,  the  closed  basins  in  Australia  aggre- 
gate 52  per  cent  of  its  area,  those  of  Africa  31  per  cent,  of  Eurasia  28  per 
cent,  of  South  America  7.2  percent,  of  North  America  3.2  per  cent.'  The 
Great  Basin  is  great  oidv  in  comparison  with  siiuil;n-  districts  of  our  own 
continent.  The  interior  district  of  the  Argentine  Repul)lic  and  Bolivia  is 
half  as  larffe  asrain,  and  thiit  of  central  Australia  exceeds  the  Great  Basin 
seven  times;  Sahara  exceeds  it  sixteen  tunes,  and  the  interior  district  of  Asia 
twenty-three  times. 

HISTORY  OF  INVESTIGATION. 

The  history  of  the  early  geographic  exploration  of  the  Great  Basin  has 
been  carefully  detailed  by  Simpson  in  the  introduction  to  the  report  of  his 
own  expedition.  In  177C  it  was  penetrated  by  Padi'e  Escalante  from  the 
southeast,  and  about  the  same  time  its  southern  rim  was  crossed  by  Path'e 
Graces,  but  it  does  not  appear  that  they  discoA-ered  the  peculiarity  of  its 
di-ainage.  From  about  1820  to  1835  the  northern  and  l)roader  portion  of 
the  basin  was  gradually  explored  by  Indian-traders,  who  learned  of  the 
existence  of  undi-ained  lakes  and  passed  the  account  from  mouth  to  mouth, 
but  made  no  maps  and  published  no  accounts  of  their  discoveries.  Cajit. 
Bonneville,  an  army  officer  on  leave,  traveling  in  the  interest  of  the  fur 
trade  but  with  the  spirit  of  exploration,  took  notes  of  geographic  value 
(1833),  which  were  put  in  shape  and  published  after  a  lapse  of  some  years 
by  Washington  Irving,  and  his  map  is  probably  the  first  Avhich  represents 
interior  drainage.  While  Irving's  account  was  in  press,  Fremont  was  en- 
gaged in  his  justly  celelmited  exploration  which  afforded  to  t\\v  world  the 
first  clear  conception  of  the  hydrography  of  the  region."  Since  that  time 
numerous  cxjjeditions,  public  and  private,  have  contributed  details,  so  that 
now  the  external  boundary  of  the  Great  Basin  is  well  known  except  at  the 
extreme  south,  and  its  internal  configuration  has  been  described  and  mapped 
throughout  four-fifths  of  its  extent. 

'  The  total  annual  rainfall  of  the  laiiil  of  the  globe,  and  the  relation  of  rainfall  to  the  annnal  dis- 
charge of  rivers.     By  John  Mnrr.ay.     Scottish  Geog.  Mag.  vol  H,  pp.  (i.VTT. 

-Report  of  the  Exploring  Expedition  to  the  Rocky  Mountains  in  the  year  1H42  and  to  Oregon  and 
North  California  in  the  years  lS4;i-'44.  by  Brovot-Capt.  J.  C.  Fremont.     Washington,  1S45. 


STANSBURY  ON  ANCIENT  SHORES.  13 

Our  knowledge  of  that  lacustrine  history  to  which  the  present  volume 
is  a  contribution  begins  ^^•ith  8tansbury.  Fremont,  finding  a  line  of  drift- 
wood a  few  feet  above  the  water  of  Great  Salt  Lake,  inferred  a  small  varia- 
tion of  its  level,  but  appears  to  have  overlooked  the  ancient  shore-lines  ter- 
racing the  mountains  round  about.  lie  described  the  coating  of  tufa  on  the 
valley  sides  near  Pyramid  Lake,  and  the  thought  that  it  might  be  a  lacust- 
rine deposit  occurred  to  liini,  but  was  deemed  inadmissible  on  account  of  the 
thickness  of  the  formation. 

Stansbury  in  1849  and  1850  made  an  elaborate  survey  of  Great  Salt 
Lake  and  its  vicinity,  meandering  its  shore,  determining  its  depth  by  a  series 
of  soundings,  and  controlling  his  work  by  a  system  of  triangulation.  Li 
his  itinerary,  while  describing  the  plain  Avliere  now  stands  Lakeside  station 
of  the  Central  Pacific  railway,  he  says: 

Tbis  extensive  flat  api)ears  to  liave  formed,  at  one  time,  the  nortliern  portion  of 
the  lake,  for  it  is  now  but  slightly  above  its  present  level.  Upon  the  slope  of  a  ridge 
connected  with  this  plain,  thirteen  distinct  successive  benches,  or  water-marks,  were 
counted,  which  had  evidently,  at  one  time,  been  washed  bj  the  lake,  and  must  have 
been  the  result  of  its  action  continued  for  some  time  at  each  level.  The  highest  of 
these  is  now  about  two  hundred  feet  above  the  valley,  which  has  itself  been  left  by 
the  lake,  owing  probably  to  gradual  elevation  occasioned  by  subterraneous  causes.  If 
this  supposition  be  correct,  and  all  api)earances  conspire  to  support  it,  there  must  have 
been  here  at  some  former  period  a  vast  inland  sea,  extending  for  hundreds  of  miles; 
and  the  isolated  mountains  which  now  tower  from  the  flats,  forming  its  western  and 
southwestern  shores,  were  doubtless  huge  islands  similar  to  those  which  now  rise 
from  the  diminished  waters  of  the  lake.' 

One  of  his  sketches  of  Fremont  Island,  reproduced  in  a  lithograph 
facing  page  102  of  his  report,  exhibits  terraces  of  the  same  sort,  and  he  says 
in  another  place  that  the  island,  which  is  "at  least  800  or  900  feet  high," 
presented  "the  appearance  of  regular  beaches,  bounded  by  what  seemed 
to  have  been  well-defined  and  perfectly  horizontal  water-lines,  at  ditferent 
heights  above  each  other,  as  if  the  water  had  settled  at  intervals  to  a  lower 
level,  leaving  the  marks  of  its  former  elevation  distinctly  traced  upon  the 
hillside.  This  continued  nearly  to  the  summit,  and  was  most  apparent  on 
the  northeastern  side  of  the  island."^ 

'Exploration  and  Survey  of  the  Valley  of  the  Great  Salt  Lake  of  Utah,  ....  by  Howard  Stans- 
bury, Capt.  Top.  Eng.,  Philadelphia,  1852,  p.  105. 
?Ibid.  p.  160. 


14  LAKE  BONNEVILLE. 

Beckwith,  who  led  a  geographic  expedition  across  the  Great  Basin  in 
1854,  makes  the  next  advance  in  the  description  of  tlie  hicustrine  phenom- 
ena, and  liis  contribution  is  so  important  that  I  quote  it  (entire: 

Tlie  olil  .shore  lines  existing  in  the  vicinity  of  tlie  Great  Salt  Lake  present  an 
interesting  study.  Some  of  them  are  elevated  but  a  few  feet  (from  five  to  twenty) 
above  the  present  level  of  the  lake,  and  are  as  distinct  and  as  well  defined  and  pre- 
served as  its  present  beaches;  and  Stansbury  speaks,  in  the  Report  of  his  exploration, 
pages  158-160,  of  driftwood  still  existing  upon  those  having  an  elevation  of  live  feet 
above  the  lake,  which  unmistakably  indicates  the  remarkably  recent  recession  of  the 
waters  which  formed  them,  whilst  their  magnitude  and  smoothly-worn  forms  as  unmis- 
takably indicate  the  levels  which  the  waters  maintained,  at  their  respective  forma- 
tions, for  very  considerable  periods. 

Ill  the  Tuilla  Valley,  at  the  south  end  of  the  lake,  they  are  so  remarkably  distinct 
and  peculiar  in  form  and  position  that  one  of  them,  on  which  we  traveled  in  crossing 
that  valley  on  the  7th  of  May,  attracted  the  observation  of  the  least  informed  team- 
sters of  our  party — to  whom  it  appeared  artificial.  Its  elevation  we  judged  to  be  twenty 
feet  above  the  present  level  of  the  lake.  It  is  also  twelve  or  fifteen  feet  above  the 
plain  to  the  south  of  it,  and  is  several  miles  long;  but  it  is  narrow,  only  affording  a 
tine  roadway,  and  is  crescent-formed,  and  terminates  to  the  west  as  though  it  had  once 
formed  a  cape,  projecting  into  the  lake  from  the  mountains  on  the  east — in  miniature, 
perhaps,  not  unlike  the  strip  of  laud  dividing  the  sea  of  Azoff  from  the  Putrid  sea. 
From  this  beach  the  Tuilla  Valley  ascends  gradually  towards  the  south,  and  in  a  few 
miles  becomes  partly  blocked  up  by  a  cross-range  of  mountains,  with  passages  at  either 
end,  however,  leading  over  quite  as  remarkable  beaches  into  what  is  known,  to  the 
Mormons,  as  Rush  Valley,  in  which  there  are  still  small  lakes  or  ponds,  once,  doubt- 
less, forming  part  of  the  Great  Salt  Lake. 

The  recessions  of  the  waters  of  the  lake  from  the  beaches  at  these  comparatively 
slight  elevations,  took  place,  beyond  all  doubt,  within  a  very  modern  geological  period; 
and  the  volume  of  the  water  of  the  lake  at  each  subsidence — by  whatever  cause  pro- 
duced, and  whether  by  gradual  or  spasmodic  action — seems  as  plainly  to  have  been 
diminished;  for  its  present  volume  is  not  sufficient  to  form  a  lake  of  even  two  or  three 
feet  in  depth,  over  the  area  indicated  by  these  shores,  and,  if  existing,  would  be  annu- 
ally dried  up  during  the  summer. 

These  banks — wiiich  so  clearly  seem  to  have  been  formed  and  left  dry  within  a 
period  so  recent  that  it  would  seem  impossible  for  the  waters  which  formed  them  to 
have  escaped  into  the  sea,  either  by  great  convulsions,  opening  passages  for  them,  or 
bj'  the  gradual  breaking  of  the  distant  shore  (rim  of  the  Basin)  and  draining  them  ofi", 
without  having  left  abundant  records  of  the  escaping  waters,  as  legible  at  least  as  the 
old  shores  they  formed — are  not  i)eculiar  to  the  vicinity  of  this  lake  of  the  Basin, 
but  were  observed  near  the  lakes  in  Franklin  Valley,  and  will  probably  be  found 
near  other  lakes,  and  in  the  numerous  small  basins  which,  united,  form  the  Great 
Basin. 

But  high  above  these  diminutive  banks  of  rei-cnt  date,  on  the  mountains  to  the 
east,  south  and  west,  and  on  the  islands  of  the  (iieat  Salt  Lake,  formations  are  seen, 
preserving,  apparently,  a  uniform  elevation  as  far  as  the  eye  can  extend — formations 


BECK  WITH  ON  ANCIENT  SHORES.  15 

on  a  magnificent  scale,  wliicli,  hastily  examined,  seem  no  less  unmistakably  tlian  tbe 
former  to  indicate  tbeir  sUore  origin.  Tliey  are  elevated  from  two  or  three  hundred  to 
six  or  eight  hundred  feet  above  the  i)resent  lake;  and  if  upon  a  thorough  examination 
they  prove  to  be  ancient  shores,  I  hey  will  perhaps  afford  (lieing  easily  traced  on  the 
numerous  mountains  of  the  Basin)  the  means  of  determining  the  character  of  the  sea 
by  which  tbey  were  formed,  whether  an  internal  one,  subsequently  drained  off  by  the 
breaking  or  wearing  away  of  the  rim  of  the  Basin — of  the  existence  of  wliicli  at  any 
time,  in  the  form  of  continuous  elevated  mountain  chains,  there  seems  at  prestiit  but 
little  ground  for  believing — or  an  arm  of  the  main  sea,  which,  with  the  continent,  has 
been  elevated  to  its  present  position,  and  drained  by  the  successive  stages  indicated 
by  these  shores.' 

A  year  earlier  Blake  explored  the  Colorado  desert  between  San  Diego 
and  Fort  Yiima,  finding  unmistakable  evidence  of  its  former  occupation  by 
a  lake.  He  observed  a  shore  line,  tufa  dejiosits,  and  lacustrine  clays,  and 
in  the  clays  and  tufa,  as  well  as  scattered  over  the  sitrface  of  the  desert,  he 
found  fresh-water  shells,  and  a  single  brackish  shell,  Gnathodoii.  His  de- 
scription and  disctission  are  full  and  eminently  satisfactory,  Init  his  expla- 
nation takes  the  lake  he  describes  out  of  the  field  of  present  interest,  for  he 
shows  that  only  its  disappearance  and  not  its  origin  is  ■  to  be  ascribed  to 
climate.  The  lake  basin  was  created  by  the  growth  of  the  delta  of  the  Col- 
orado River,  which  was  built  across  the  Gulf  of  California,  separating  a 
portion  of  its  upper  end.  When  the  river,  shifting  on  its  delta,  is  turned  to 
the  right,  a  lake  is  maintained  behind  the  barrier,  a  lake  with  outlet  to  the 
Gulf,  and  therefore  fresh.  When  the  river  turns  to  the  left,  it  flows  directly 
to  the  Gulf,  and  the  lake  is  dried  away.  The  latter  is  the  present  and  his- 
toric condition,  but  occasionally  at  extreme  flood  a  portion  of  the  river's 
water  has  been  known  to  flow  for  many  miles  toward  the  desiccated  basiu.^ 

Simpson,  exploring  for  wagon  routes  in  the  broadest  part  of  the  Great 
Basin,  in  1859,^  observed  in  Cedar  and  Rush  valleys  the  same  water  lines 
that  had  been  seen  by  Stansbury  farther  north;  and  Henry  Engelniann, 
the  geologist  of  his  party,  noted  not  only  shore  terraces  but  lacustrine  silt 
and  tufa  and  fresh-water  shells.     He  points  out  that  the  saltness  of  the 

'Explorations  .  .  .  from  the  month  of  the  Kansas  River,  Mo.,  to  the  Sevier  Lake,  in  the  Great 
Basin.  By  Lieut.  E.  G.  Becliwith.  Foot  note  to  p.  97.  In  Pacifip,  Railroatl  reports,  vol.  2,  Washing- 
ton, 185.5. 

» Geological  Report,  by  William  P.  Blake.  In  Pacific  Railway  Reports,  vol.  5,  18.56,  pp.  97-99, 
236-239. 

'Explorations  across  the  Great  Basin  of  the  Territory  of  Utah  for  a  direct  wagon-route  from 
Camp  Floyd  to  Genoa,  in  Carson  Valley,  in  1859,  by  Captain  J.  H.  Simpson.     Washington,  1876. 


16  LAKE  BONNEA^LLE. 

Basin  lakes  is  inconsistent  witli  the  prevalent  impression  that  they  ])Ossess 
subterranean  outlets,  and  comparing  their  former  with  their  present  extent, 
refers  the  difference  to  climate.  lie  arj^ues  that  tlu;  ])reseut  geographic  con- 
ditions tend  to  the  diminution  of  rainfall,  and  that  under  them  the  basin  has 
become  progressively  more  and  more  arid.  But  there  is  nothing  in  his  dis- 
cussion serving  to  explain  the  greater  humidity  of  the  preceding  age. 

The  reports  of  Simpson  and  Engelmann,  though  prepared  in  manu- 
script immediately  after  the  completion  of  their  exploration,  were  not  printed 
until  1S78,  and  in  the  mean  time  many  observers  saw  the  lake  vestiges  ami 
wrote  u})on  them.  Whitney,  visiting  Mono  Lake  in  lS(i3,  and  noticing  old 
shore-lines  rising  in  a  series  to  the  height  of  (JOG  feet  above  the  water,  raised 
the  question — for  many  years  unanswered — whether  the  old  lake  was  con- 
fined to  the  j\Iono  Valley  or  communicated  with  lakes  in  other  valleys  of  the 
Great  Basin,  and  pointed  out  that  whatever  conditions  produced  the  ancient 
glaciers  of  the  adjacent  Sierra  were  competent  to  expand  the  lake.^  If<»y- 
den  in  1870  examined  the  old  shore-lines  in  the  immediate  \ncinity  of  Great 
Salt  Lake,  coiTCctly  correlated  them  with  lacustrine  deposits  at  various 
points,  sliowed  their  recency  as  compared  to  the  later  Tertiary  beds  of  the 
vicinity,  and  referred  them  to  the  Quaternary.  He  also  found  shells  in  the 
de])osits,  and  from  their  character  recognized  the  freshness  of  the  old  lake.^ 
Bradley,  two  years  later,  recognized  the  broad  terraces  flanking  (^gden 
River  and  other  streams  of  the  vicinity  as  deltas  built  by  the  same  streams 
in  the  ancient  lake,  observed  that  the  Ogden  delta  deposits  extended  into 
the  mountain  canyon  of  the  river,  and  drcAv  the  important  conclusion  that 
before  the  age  of  the  high  terraces  Great  Salt  Lake  was  not  far,  if  at  all, 
above  its  present  level.'  About  the  same  time  Poole  made  additional  oljscr- 
vations  on  the  shore-lines  of  the  same  basin  and  tracud  thnn  as  far  westward 
as  the  Deep  Creek  Mountains.* 

The  observations  of  Hay  den,  Bradley,  and  Poole  were  independent 
and  original,  and  by  reason  of  priority  of  publication  they  belong  to  the 

'Geol.  Surv.  of  California,  Geology,  vol.  1,  l)y  J.  D.  Wbituey.      Pliilailclpliia  ISfi'i,  pi>.  4ril-J,'i2. 

2U.  S.  Geol.  Surv.  of  Wyomiuj,'.  .  .  1870,  by  F.  V.  Hayilen.  Wa.sliiut;ti)ii,  187'2,  pp.  161),  170, 
172,  175. 

^  Report-  of  Frauk  H.  Bradley,  in  U.  S.  Geol.  Surv.  of  the  Territories,  Ropt.  for  1S72.  Washing- 
ton, 187:!,  pp.  192,  11)6. 

■•The  Great  American  Desert,  by  Henry  S.  Poolo  ;  Proc.  Nova  Scotia  Inst.  Nat.  Sci.,  vol.  3,  pp. 
208-220. 


WHITNEY,  KING,  HAYDEN.  17 

history  of  the  subject,  but,  as  ah-ead}-  mentioned,  they  were  partially  an- 
ticipated by  those  of  Simpson  and  Engelmann,  and  wholly  anticipated  by 
those  of  King,  Hague  and  Emmons,  the  geologists  of  the  Fortieth  Parallel 
Exploration.  The  work  of  tliis  corps  covered  a  belt  one  hundred  miles 
broad,  spanning  the  Great  Basin  in  its  broadest  part,  and  within  this  belt 
the  Pleistocene  lakes  were  studied  and  for  the  first  time  approximately 
mapped.  It  was  shown  that  the  corrugated  surface  of  the  Great  Basin  in 
this  latitude  is  higher  in  the  middle  than  at  the  east  and  west  margins,  war- 
ranting a  general  subdivision  into  the  Utah  Basin,  the  Nevada  Plateau  and 
the  Nevada  Basin;  that  the  Utah  Basin  formerly  contained  a  large  lake, 
Bonneville,  extending  b(jtli  north  and  south  beyond  the  belt  of  survey;  that 
the  Nevada  Basin  contained  a  similar  lake,  Lahontan,  likewise  exceed- 
ing the  limits  of  the  belt;  and  that  the  valleys  of  the  central  plateau  held 
within  the  belt  no  less  than  eight  small  Pleistocene  lakes.  The  mechanical 
sediments  and  chemical  deposits  of  the  lakes  were  studied,  and  were  ascer- 
tained to  overlie  subaerial  gravels,  thus  proving  that  a  dry  climate  had  pre- 
ceded the  humid  climate  of  the  lake  epoch;  and  it  was  inferred  from  the 
chemical  deposits  of  Lake  Lahontan  that  the  lake  had  been  twice  formed 
and  twice  dried  away.^ 

The  field  work  that  afforded  this  important  body  of  information  was 
performed  chiefly  in  the  years  1867-70,  but  publication  was  delayed  till 
1877-78.  In  1872  Howell  and  the  writer,  traveling  Avith  topographic  par- 
ties of  the  Wheeler  Survey,  traversed  the  Utah  Basin  on  many  lines,  and 
our  reports,  printed  in  1874  and  1875,  contained  an  account  of  Lake  Bon- 
neville, the  extent  of  Avhicli  we  were  able  to  indicate  with  inconsiderable 
error,  and  to  which  the  writer  gave  a  name.^  Thus,  by  an  accident  of  pub- 
lication. King  and  his  colleagues  lost  that  literary  priority  in  regard  to  Lake 
Bonneville  to  which  they  were  fairly  entitled  by  priority  of  investigation. 

'Geol.  Expl.  of  the  40th  Parallel.  Vol.  1,  Systematic  Geology,  by  Clarence  King.  Washington, 
1878;  vol.  2,  Descriptive  Geology,  by  Arnold  Hague  and  S.  F.  Emmons.     Wasliington,  1877. 

*  Prelim.  Geol.  Rept.  by  G.  K.  Gilbert;  Appendix  D  to  Progress  Rept.  Expl.  and  Sur.  W.  of 
the  100th  Mer.  in  1872.     Washington,  1874,  pp.  49-50. 

Explorations*  and  Surveys  west  of  the  100th  Meridian,  vol.  3,  Geology.     Washington,  1H75.     Part 
1,  by  G.  K.  Gilbert,  treats  of  Lake  Bonneville  on  pp.  88-104.     Part  3,  by  Edwin  E.  Howell,  treats  of 
Lake  Bonneville  on  pp.  249-251. 
MON   I 2 


18  LAKE  BONNEVILLE. 

In  1877  Pealc  observed  shore  terraces  in  various  parts  of  (Jaolie  valley.' 
From  1875  to  1878  I  spent  each  summer  in  Utah  as  a  mem1)er  of  the 
Powell  survey,  and  found  many  ()i)it(trtunities  in  connection  with  other  work 
to  continue  the  study  of  Lake  Bonue\'ille.  This  \vas  especiall}'  the  case  in 
1877,  when  the  duty  of  gathering  inforaialion  as  to  the  irrigable  land  of  the 
basin  of  Great  Salt  Lake  led  me  all  about  the  margin  of  the  Salt  Lake  desert. 
When  the  corps  for  western  surveys  were  reorganized  in  1879, 1  was  placed 
in  charge  of  the  Division  of  the  Great  Basin,  with  tlie  understanding  that  the 
Pleistocene  lakes,  previously  investigated  only  in  an  incidental  way,  should 
fonn  a  principal  subject  of  study.  Late  in  the  season  some  months  were 
spent  in  the  field,  with  Mr.  W.  D.  Johnson  as  assistant;  and  a  corps  was 
oi'ganized  the  following  year.  Of  this  coi'ps,  Mr.  Israel  C.  Russell  was  \)vin- 
cipal  assistant,  and  he  remained  with  the  work  from  first  to  last,  l^eing 
assigned  independent  investigations  after  the  first  season,  ilessrs.  H.  A. 
Wheeler,  W.  J.  McGee,  and  Geo.  M.  Wright  took  pai-t  in  the  geologic  work 
for  shorter  periods.  Messrs.  Gilbert  Thompson,  Alljcrt  L.  Webster,  Willard 
D.  Johnson,  and  Eugene  Ricksecker,  associated  with  the  work  at  various 
times  as  topographers,  and  Messrs.  Fred.  D.  Owen,  J.  B.  Bernadou,  and  E. 
R.  Trowbridg-e,  temporarily  attached  to  field  jjarties  as  general  assistants, 
all  contril^uted  to  the  mapping  and  illustration  of  the  lake  jjhenomena. 

The  field  work  of  the  year  1880  was  in  the  Bonneville  Basin,  and  little 
was  afterAvard  done  in  that  area.  In  1881  Mr.  Russell  made  a  ])relinnnary 
e.\annnation  of  the  vestiges  of  Lake  Lahoiitau  in  the  Nevada  IJasin  and  of 
the  Mono  Basin,  aiid  in  the  following  spring  extended  his  reconnaissance 
to  the  lake  basins  of  southeastern  Oregon.  I  was  called  to  Washington  in 
the  spring  of  1881  on  duty  supposed  to  be  temporai-y,  but  remained  there 
until  the  following  year,  w  hen  the  work  of  the  Surve},  pre\iously  restricted 
to  the  western  l\'rritories,  was  extended  l)y  C<->ngress  to  the  eastern  States 
also.  As  the  enlargement  of  field  and  function  was  not  accompanied  l)yan 
equivalent  increase  of  funds,  it  became  necessary  to  curtail  the  western 
work  of  the  Survey,  and  it  was  decided  to  stop  the  investigation  of  the 
Pleistocene  lakes  as  soon  as  this  could  lie  done  witliout  •'•reat  sacrifice  of 


'  Keport,  of  A.  C.  Peale,  in  U.  S.  GeqJ.  Surv.  of  tho  Territories  for  1877,  Washiugtou,  1879,  pp. 
603-606. 


U  S. GEOLOGICAL    SURVKY 


LAKE  BONNE^/ILLE      PL  m 


113° 


112° 


111° 


42«^ 


41' 


39" 


38' 


MAP  OF 

'L/\KE  BONNEMLLE 

showing 
ROUTES   OF   THA\^EL 


Routes  by  G.  K-Gilbert    ^^       "* 
JVdditional  routes  by  Assistants 


Julius  Bien  A  Iji.lith 


Drown  by  C  TfaompBon 


RUSSELL,  DANA,  GALL.  19 

material  already  acquired.  Mr.  Russell  completed  the  study  of  the  Lalion- 
tau  and  Mono  Basins  by  the  close  of  the  season  of  1883  and  then  returned 
east.  I  made  a  single  excursion  in  the  summer  of  1883,  devoting  a  few 
weeks  to  supplementary  observations  in  the  Bonneville,  Lahontan,  and  Mono 
Basins,  and  visiting  Owens  Valley  to  examine  the  geologic  features  of  the 
Inyo  earthquake.  The  examination  of  the  more  southerly  valleys  of  the 
Great  Basin,  the  study  of  the  brines  and  saline  deposits,  and  the  elaborate 
measurement  of  post-Pleistocene  displacements,  are  indefinitely  deferred. 

The  results  of  the  investigation  have  been  communicated  in  a  series  of 
reports,  essays,  and  memoirs.  An  outline  of  the  Bonneville  history  was 
published  by  me  in  1882,'  and  an  essay  on  shore  topography  in  1885.^ 
Russell's  results  have  appeared  in  a  preliminary  report  on  Lake  Lahontan,^ 
reports  on  the  Oregon  basins'*  and  the  Mono  Basin, ^  and  a  monograph  on 
Lake  Lahontan.^  An  essay  on  the  Pleistocene  fresh-water  shells  ^vas  pre- 
pared and  published  by  Call,'  and  one  on  the  pseudomorph  thinolite  by 
Dana.*     The  present  publication  completes  the  series. 

'Coutributions  to  the  history  of  Lake  Bonneville:  Second  Ann.  Kept.  U.  S.  Geol.  Survey.  Wash- 
ington, 1882,  pp.  169-200. 

=  The  topographic  features  of  lake  shores:  Fifth  Ann.  Kept.  U.  S.  Geol.  Survey.  Washington, 
1885,  pp.  7.5-123. 

Adiscnssion  of  post-Bonneville  displacement  appeared  in  an  address  "The  luculcation  of  Scien- 
tific Method  by  Example,"  read  to  the  American  Society  of  Naturalists  Dec.  27,  1885,  and  printed 
in  the  Am.  Jour.  Sci.,  vol.  31,  pp.  284-291).  A  description  of  the  jointed  structure  of  the  Bonneville 
beds  was  printed  in  the  Am.  Jour.  Sci.,  3d  Series,  Vol.  23,  1882,  pp.  25-27. 

'Sketch  of  the  Geological  History  of  Lake  Lahontan  :  Third  Ann.  Kept.  U.  S.  Geol.  Survey.  Wash- 
ington, 1883,  pp.  189-235. 

^A  geological  reconnaissance  in  Southern  Oregon:  Fourth  Ann.  Rept.  U.  S.  Geol.  Survey.  Wash- 
ington, 1885,  pp.  431-164. 

•'*  Quaternary  history  of  Mono  Valley,  California :  Eighth  Ann.  Rept.  U.  S.  Geol.  Survey.  Washing- 
ton, 1880,  pp.  261-394. 

15  Geological  History  of  Lake  Lahontan  :   Mon.  U.  S.  Geol.  Survey,  No  11,  Washington,  1885,  pp.  302. 

Other  publications  by  Mr.  Kussell  containing  portions  of  the  same  material  are — 
Lakes  of  the  Great  Basin:  Science,  vol.  3,  1884,  pp  322-323. 

Dejiosits  of  Volcanic  Dust  in  the  Great  Basin  :  Bull.  Phil.  Soc,  Washington,  vol.  7,  1885,  pp.  18-20. 
Notes  on  the  Faults  of  the  Great  Basin,  .  .  . :  Bull.  Phil.  Soc.  Washington,  vol.  9, 1887,  pp.  5-8. 
The  Great  Basin.     In  Overland  Monthly,  2d  Series,  vol.  11, 1888,  pp.  420-426. 

'On  the  Quaternary  and  Recent  MoUnscaof  the  Great  Basin,  with  descriptions  of  new  forms.  By 
E.  Ellsworth  Call.  Introduced  by  a  Sketch  of  the  Quaternary  Lakes  of  the  Great  Basin,  by  G.  K. 
Gilbert.     Bull.  U.  S.  Geol.  Survey  No.  11, 1884,  56  pp. 

"A  Crystallographic  Study  of  the  Thinolite  of  Lake  Lahontan.  By  Edward  S.  Dana.  Bull.  U.  S. 
Geol.  Survey  No.  12, 1884.  29  pp. 


20  LAKE  BONNEVILLE. 


THE  BONNEVILLE   BASIN. 


The  Great  Basin  comprises  a  large  number  of  sul^sidiary  closed  basins, 
each  draining  to  a  lake  or  ])laya.  Aliout  sixty  ot"  these  could  be  enuiiicnited 
from  present  knoAvledge,  and  the  fvdl  nuiiil)er  may  be  as  high  as  one  luni- 
dred.  In  the  last  geologic  epoch  a  more  humid  climate  (■(inverted  iii;iiiy, 
or  perhaps  all,  of  these  playas  into  lakes,  and  enlarged  all  the  lakes.  Some 
lakes  overflowed  the  rims  of  their  basins,  becoming  tributary  to  others;  and 
the  lakes  of  adjacent  basins  in  many  instances  expanded  until  they  l)ecaine 
continent.  A  few  of  the  overflowing  lakes  discharged  across  the  rim  of  the 
Great  Basin,  thus  becoming  tributary  to  the  ocean,  and  subtracting  their 
catchment  basins  from  the  district  of  interior  drainage.  In  the  remaining 
portion  of  the  district  the  nmnber  of  independent  drainage  areas  A\'as  reduced 
by  coalescence. 

The  laro-est  of  the  confluent  lakes  Avere  formed  at  the  eastern  and 
western  raai-gins  of  the  Great  Basin,  being  separated  by  the  plateau  of 
eastern  Nevada.  Lake  Lahontan  at  the  west  was  fed  chiellA-  In'  the  snows 
of  the  Sierra  Nevada,  Lake  Bonneville  at  the  east  by  those  of  the  Wasatch 
and  Uinta  mountains. 

The  catchment  basin  of  Lake  Bonneville  comprises  that  part  of  the 
Great  Basin  lying  east  of  the  Gosiute,  Snake,  and  Piiion  mountains  of  east- 
ern Nevada — an  oblong  ai-ea  embracing  about  five  degrees  of  latitude  and 
three  of  longitude,  and  containing  about  54,000  squai-e  miles,  or  the  fourth 
part  of  the  area  of  the  Great  Basin.  Its  western  two-thirds  may  be  described 
as  a  plain  ranging  in  altitude  from  4,200  to  5,500  feet  above  tide,  and  more 
or  less  interrupted  by  short  moiuitain  ranges  trending  north  and  south.  At 
the  north,  where  the  mountains  are  comparatively  few  and  small,  the  barren 
plain  is  called  the  Great  Salt  Lake  Desert,  and  similar  open  stretches  at  the 
south  are  named  the  Sevier  Desert  and  the  Escalante  Desert.  The  eastern 
third  is  much  higher,  including  the  lofty  Wasatch  Range  and  its  dependen- 
cies, the  western  end  of  the  still  loftier  Uinta  Range,  and  the  western  jjart 
of  the  district  of  the  High  Plateaus.  Several  peaks  of  the  Wasatch  and 
Uinta  Mountains  rise  above  the  level  of  lL*,000  feet,  and  the  High  Plateaus 
culminate  near  Beaver  in  the  Tusliar  ridge  with  peaks  of  similar  altitude. 


THE  BONNEVILLE  BASIN.  2l 

The  eastern  uplands  are  the  only  important  condensers  of  moisture, 
and  from  them  flow  a  sj'stem  of  rivers  whose  Avaters  are  eva])orated  in  the 
salt  lakes  of  the  lowlands.  The  Bear,  the  Weber,  and  the  Provo-Jordan 
have  their  principal  sources  in  the  Uinta  Mountains,  and  break  through  the 
Wasatch  Range  on  their  way  to  Great  Salt  Lake.  One  of  the  upper  val- 
leys traversed  by  the  Bear  River  contains  Bear  Lake,  a  body  of  fresh  water; 
and  Utah  Lake,  likewise  fresh,  receives  the  Provo  and  discharges  the  Jor- 
dan. The  Sevier  River,  after  flowing  1,50  miles  nortlnvard  among  the 
plateaus,  receives  the  San  Pete  from  the  nortli  and  then  turns  westward 
to  Sevier  Lake,  the  saline  of  the  Sevier  Desert. 

The  eastern  uplands  are  better  timbered  than  any  other  part  of  the  Great 
Basin.  The  upland  valleys  are  fertile,  but  having  a  climate  too  cool  for 
agriculture  are  devoted  to  grazing  and  maintain  only  a  scant  population. 
The  western  plain  is  infertile  by  reason  of  aridity,  and  is  almost  without 
inhabitants.  The  lower  valleys  of  the  rivers,  where  they  issue  from  the 
uplands  upon  the  plain,  have  a  climate  suited  for  agriculture,  are  rendered 
fertile  by  irrigation,  and  constitute  a  habitable  zone,  over  which  the  Mor- 
mon community  has  spread. 

To  understand  fully  the  topographic  relations  described  above,  the 
reader  should  examine  the  large  map  of  Lake  Bonneville  (in  a  pocket 
attached  to  the  cover  of  this  volume),  where  the  reliefs  are  expressed  by 
contour  lines  at  each  1,000  feet;  and  also  Plate  XII,  whereon  are  marked 
the  boundary  of  the  Bonneville  Basin  and  tlie  boundaries  of  the  equivalent 
group  of  smaller  basins  as  they  exist  at  the  present  time.  He  will  find  also 
that  the  plate  supplements  the  expression  of  the  distribution  of  the  uplands, 
by  contrasting  the  area  above  7,000  feet  with  the  area  below;  and  he  can 
learn  from  it  more  readily  than  through  words  the  relation  of  the  basin  to 
the  political  diA-isions  of  the  country.  By  turning  again  to  Plate  II  he  will 
see  that  the  Bonneville  basin  adjoins  interior  drainage  only  on  the  west; 
its  northern  rim  parts  it  from  the  basin  of  Snake  River,  a  branch  of  the 
Columbia,  its  eastern  and  southern  from  the  basin  of  the  Colorado  of  the 
West.  The  more  important  streams  heading  near  the  northern  rim  and 
flowing  to  the  Snake  are  the  Salt,  Blackfoot,  Portneuf,  Bannack,  and  Raft. 
In  the  eastern  rim  rise  Black's  Fork,  the  Uinta,  and  the  Price,  all  tributary 


22  LAKE  BONNEVILLE. 

to  the  Green  before  it  joins  the  Colorado,  tind  the  San  Rafael,  Fremont,  and 
Escalante,  immediate  tributaries  of  the  Colorado.  The  Paria,  Kanab,  and 
Virffen  flow  to  the  Colorado  from  the  southern  rim. 

CHRONOLOGIC  NOMENCLATURE. 

The  geologic  period  to  which  the  Bonneville  history  has  been  referred 
has  three  names  in  good  standing,  Quaternary,  Pleistocene,  and  Glacial. 
Each  name  varies  more  or  less  in  scope  as  used  by  different  authors,  but  as 
ordinarily  understood  the  three  are  strictly  synonymous.  In  earlier  Avrit- 
ings  I  have  preferred  Quaternary,  in  the  present  I  prefer  Pleistocene. 

No  vital  principle  is  involved  in  either  preference,  and  indeed  I  am  not 
of  those  who  clamor  for  the  rights  of  words.  In  my  judgment  words  have 
no  rights  which  the  users  of  words  are  bound  to  respect.  The  claim  of  a 
word  for  preference  rests  only  on  its  utility — its  convenience  for  the  com- 
munication of  thought. 

Glacial  connotes  glaciers,  and  was  a  convenient  name  while  it  was  sup- 
posed that  a  cold  climate  marked  the  whole  period.  But  now  that  interrup- 
tions of  that  climate  are  recognized,  it  is  more  convenient  to  speak  of  glacial 
epochs  and  interglacial  epochs  of  the  Quaternary  or  Pleistocene  })eriod. 

Quaternary  connotes  a  fouribld  classification,  and  is  coordinate  \vith 
Tertiary.  Pleistocene  suggests  by  its  termination  coordination  with  the 
subdivisions  of  the  Tertiary.  Using  the  scale  of  time-nouns  adopted  by  the 
International  Congress  of  Geologists,  the  Quaternary  is  an  era,  having  the 
classificatory  rank  of  the  Tertiary  era,  and  the  Pleistocene  is  a  period,  rank- 
ing with  the  Eocene  period.  It  is  generally  believed  that  the  Pleistocene  is 
comparable  in  ])oint  of  diiration  with  one  of  the  periods  of  the  Tertiar}*  era, 
being  less  rather  than  greater,  and  those  who  advocate  the  emplopnent  of 
the  name  Quaternary  recognize  the  Quaternary  era  as  one  containing  but  a 
single  period.  The  time  division  with  which  we  have  to  deal  is,  then,  from 
eveiy  point  of  view,  a  "period,"  and  it  is  believed  that  the  use  of  the  name 
Pleistocene  Period  involves  a  minimum  amount  of  implication  as  to  higher 
classification,  a  subject  whose  discussion  is  not  here  contemplated. 


CHAPTER    II. 

THE  TOPOGRAPHIC  FEATURES  OF  LAKE  SHORES. 

It  has  been  assumed  in  the  i)veceding-  pag-es  that  valleys  trom  which 
lakes  have  recently  disappeared  are  characterized  l)y  certain  features 
wherebv  that  lact  can  he  recognized.  Perhaps  no  one  observant  of  natural 
phenomena  will  disjjute  this.  But  there  is,  nevertheless,  some  diversity  of 
opinion  as  to  what  are  the  peculiar  characters  to  which  lakes  give  rise;  and 
especially  has  the  true  interpretation  of  certain  local  topographic  features 
been  mooted,  some  geologists  ascribing  them  to  waves,  and  others  to  dif- 
ferent agencies. 

In  the  investigation  of  our  ancient  lake,  it  has  been  found  necessary 
not  only  to  discriminate  from  all  other  topographic  elements  the  features 
created  by  its  waves,  but  also  to  ascertain  the  manner  in  which  each  was 
produced,  so  as  to  be  able  to  give  it  the  proper  interpretation  in  the  recon- 
struction of  the  history  of  the  lake.  It  is  proposed  in  this  chapter  to  pre- 
sent the  more  general  results  of  this  study,  describing  in  detail  the  various 
elements  which  constitute  shore  topography,  explaining  their  origin,  so  far 
as  possible,  and  finally  contrasting  them  with  topographic  features  of  other 
origin  which  so  far  simulate  them  as  to  occasion  confusion. 

The  play  of  meteoric  ag-ents  on  the  surface  of  the  land  is  unremitting, 
so  that  there  is  a  constant  tendency  to  the  production  of  the  forms  charac- 
teristic of  their  action.  All  other  forms  are  of  the  nature  of  exceptions, 
and  attract  the  attention  of  the  observer  as  requiring  explanation.  The 
shapes  wrought  by  atmospheric  erosion  are  simple  and  symmetric  and  need 
but  to  be  enumerated  to  be  recognized  as  normal  elements  of  the  sculpture 

23 


24  LAKE  BONNEVILLE. 

of  the  land.  Along  each  di-aiuage  line  there  is  a  gradual  and  gradually 
increasing  ascent  from  mouth  to  source;  and  this  law  of  increasing  acclivity 
applies  to  all  branches  as  well  as  to  the  mnin  stem.  Between  each  ))!iir  of 
adjacent  drainage  lines  is  a  ridge  or  hill,  standing  midway  and  roundcMl  at 
the  top.  Wherever  two  ridges  join  there  is  a  sunnnit  higher  than  the  adja- 
cent portion  of  either  ridge;  and  the  highest  summits  of  all  arc  those  which, 
measuring  along  lines  of  drainage,  are  most  remote  from  the  ocean.  The 
crests  of  the  ridges  are  not  horizontal  but  undulate  from  summit  to  summit. 
There  are  no  sharp  contrasts  of  slope;  the  concave  profiles  of  the  drainage 
lines  change  their  inclination  little  by  little  and  merge  by  a  gradual  transi- 
tion in  the  convex  profiles  of  the  crests  and  sununits. 

The  factor  Avhich  most  frequently,  and  in  fact  almost  universally,  inter- 
rupts these  simple  curves  is  heterogeneity  of  terrane.  Under  the  infiuence 
of  this  factor,  just  as  in  the  case  of  a  homogeneous  terrane,  the  declivities 
adjust  themselves  in  such  way  as  to  oppose  a  maxinmm  resistance  to  erosion; 
and  with  diversit}'  of  rock  texture  this  adjustment  involves  diversity  of  form. 
Hard  rocks  survive,  while  the  soft  ai"e  eaten  away.  Peaks  and  clifts  are 
})ro<luced.  The  apices  are  often  angular  instead  of  roUnded.  Profiles 
exhil)it  abrupt  changes  of  slope.  Flat-topped  ridges  appear,  and  the  dis- 
tribution of  maximum  sununits  becomes  in  a  measure  independent  of  the 
leno'th  of  drainao^e  lines. 

A  second  factor  interrupting  the  continuity  of  erosion  profiles  is  up- 
heaval; and  this  produces  its  effects  in  two  distinct  ways.  First,  the  general 
uprising  of  a  broad  tract  of  land  affects  the  relation  of  the  drainage  to  its 
point  of  discharge  or  to  its  base  level,  causing  corrasion  liy  streams  to  be 
more  rapid  than  the  general  Avaste  of  the  surface  and  producing  i-anyons 
and  terraces.  Second,  a  local  uprising  by  means  of  a  fault  produces  a  clifi" 
at  the  margin  of  the  uplifted  tract;  and  above  this  cliff  there  is  sometimes 
a  terrace. 

A  third  disturbing  factor  is  glaciation,  the  cirques  and  moraines  of 
which  are  distinct  from  anything  wrought  liy  pluA-ial  erosion;  ;nid  a  fourth 
is  found  in  eruption. 

The  products  of  all  these  agencies  except  the  last  have  been  occasionally 
confused  with  the  phenomena  of  shores.     The  beach-lines  of  Glen  Roy  have 


SCULPTURE  OF  THE   LAND.  25 

been  called  river  terraces  and  moraine  terraces.  The  cliffs  of  the  Downs  of 
Eno-land  have  been  ascribed  to  shore  waves.  Grlacial  moraines  in  New 
Zealand  have  been  interpreted  as  shore  terraces.  Beach  ridges  in  t)ur  own 
conntry  have  been  described  as  glacial  moraines,  and  fault  terraces  as  well 
as  river  terraces  have  been  mistaken  for  shore-marks. 

In  the  planning  of  engineering  works  for  the  im})rov('iuent  and  protec- 
tion of  harbors,  it  is  of  })riine  importance  to  understand  the  natural  pntcesses 
by  which  coast  features  are  produced  and  modified,  iuid  this  necessity  has 
led  t( »  the  production  by  engineers  of  a  large  though  widely  scattered  litera- 
ture on  coast-forming  agencies.  Geologists  also  require  for  the  interpre- 
tation of  strata  originating  as  coast  deposits  an  understanding  of  the  metliods 
of  coastal  degradation  and  coastal  deposition,  and  from  their  point  t)f  view 
there  has  arisen  an  independent  literature  on  the  subject.  The  physical 
theory  of  water  waves  required  alike  by  engineers  and  geologists  has  been 
developed  by  physicists,  and  has  its  own  literature.  The  three  groups  of 
writers  have  so  thoroughly  traversed  the  subject  of  shore  })rocesses  that  the 
present  chapter  would  have  need  to  demonstrate  its  raison  d'etre  were  it  not 
that  the  general  subject  has  as  yet  received  no  compendious  and  systematic 
treatment  in  the  English  language. 

It  happens,  moreover,  that  the  present  treatment  of  the  subject  has  its 
own  peculiar  point  of  view,  and  is  in  large  part  independent.  During  the 
progress  of  the  field  investigation  I  was  unaware  of  the  greater  part  of  the 
literature  mentioned  above,  having  indeed  met  with  but  one  important 
pa})er,  that  in  which  Andrews  describes  the  formation  of  beaches  at  the  head 
of  Lake  Michigan,  and  I  was  induced  by  the  requirements  of  my  work  to 
develop  the  philosophy  of  the  subject  ab  initio.  The  theories  here  presented 
had  therefore  received  approximately  their  present  form  and  arrangement 
before  they  were  compared  with  those  of  earlier  writers.  They  are  thus 
original  without  being-  novel,  and  their  independence  gives  them  confirma- 
tory value  so  far  as  they  agree  with  the  conclusions  of  others. 

The  peculiarity  of  the  point  of  view  lies  in  the  fact  that  the  phenomena 
chiefly  studied  are  fossil  shore-lines  instead  of  modern.  The  bodies  of  water 
to  which  they  pertain  having  disappeared,  the  configuration  of  the  sub- 
merged portion  is  directly  seen  instead  of  being  interpreted  from  laborious 


26  LAKE  BONNEVILLE. 

soundiiifjs.  There  are,  moreover,  natural  sections  of  the  deposits,  exposed 
by  subsequent  erosion,  and  these  reveal  features  of  internal  structure  or 
anatomy  quite  as  important  to  the  geologist  as  the  features  of  morphology. 
The  literature  of  shore-lines  is  so  feebl}-  connected  by  cross  reference,  and 
portions  of  it  have  been  discovered  in  places  .so  unexpected,  that  the  writer 
fears  many  important  c.ontril)utions  have  escaped  his  attention.  Within  the 
range  of  his  reading,  the  earliest  discussions  of  value  are  by  Beaumont^  and 
De  la  Beche,'-  and  it  must  be  admitted  that  the  writers  of  gef)logic  manuals 
now  in  use  have  improved  very  little  upon  their  presentation.  Fleming,  in 
an  essay  on  the  origin  and  preservation  of  the  harbor  of  Toronto,^  set  forth 
the  process  of  littoral  transportation  witli  admirable  clearness;  and  Andrews, 
who  appears  to  have  reached  his  conclusions  by  independent  observation, 
added  to  the  theory  of  littoral  transportation  an  important  factor  in  the 
theory  of  littoral  deposition.''  Mitchell,  in  an  essay  on  tidal  marshes,'^  inci- 
dentally describes  the  growth  of  the  protecting  barrier.  A  general  treatise 
by  Cialdi"  gives  a  systematic  discussion  of  coast  processes  from  the  engi- 
neer's point  of  view,  and  reviews  the  Italian  literature  of  the  subject;  and 
a  shorter  paper  by  Keller^  has  a  similar  scope.  Richthofen,  in  liis  manual 
of  instruction  to  scientific  travelers,  treats  analytically  and  at  length  of  the 
work  of  waves  in  conjunction  with  tides,  and  discusses  a  subsiding  conti- 
nent.* The  theory  of  waves  has  been  developed  experimentally  by  a  com- 
mittee of  the  British  Association,  with  J.  Scott  Russell  as  reporter;®  and  it 
is  analytically  treated  by  Airy'"  and  Rankine." 

'  Legons  de  geologic  pratiiiiie.     Par  Elie  de  Beaumont.     Vol.  1,  pp.  221-253,  Paris,  ISJ.^. 

=  A  Geological  Manual.     By  Henry  T.  De  la  Becbe.     3d  edition,  enlarged,  London,  1833,  pp.  (17-91. 

The  Geological  Observer.     By  tbe  same.     London,  18.'>1,  pp.  49-117. 

'Toronto  Harbor — its  fonnation  and  preservation.  By  Sandford  Fleming,  C.  E.  :  Canadian 
Journal,  vol.  2,  ls54,  pp.  103-107,  223-230.  Reprinted  witb  additions  as  Report  on  Preservation  and 
Improvement  of  Toronto  Harbor.     In  Supplen^ent  to  Canadian  Journal,  1854,  pp.  15-29. 

■"Tbe  North  American  Lakes  considered  as  cbronometers  of  post-Glacial  time.  By  Dr.  Edmund 
Audrows.     Trans   Chicago  Acad.  Sci.,  Vol.  2,  pp.  1-23. 

i^On  the  reclamation  of  tide-lands  and  its  relation  to  navigation.  By  Henry  Mitchell.  Appen- 
dix No.  5,  to  Rept.  U.  S.  Coast  .Survey  for  l-^GO.     Washington,  1872,  pp.  75-104. 

«Snl  moto  ondoso  del  mare  e  sn  le  correnti  di  esso  specialmente  sii  (juello  littorali.  Alessandio 
Cialdi,  Rom.n,  18G6. 

'Studien  nberdie  Gestaltung  dcr  Sandku.sten,  etc.,  11.  Keller,  Berlin,  18S1. 

'Fiihrer  fiir  Forscbuugsrciscnde,   vou  Ferdinand  Freiherr  von  Richthofen.      Berlin,  1880,  pp. 

336-365. 

9  Report  of  the  Committee  on  Waves,  by  Sir  John  Robinson,  and  John  Scott  Russell,  Reporter: 
Rept.  British  Ass.  Adv.  Sci.,  7th  meeting,  1837,  pp.  417-496. 

'"G.  B.  Airy,  Vol.  V,  Ency.  Metrop. 

"W.  J.  McQ.  Rankine,  Philos.  Trans.  Royal  Soc.     London,  vol.  153,  1863,  pp.  127-13-'. 


LAND  SHAPING  AND  SHORE  MAKING.  27 

In  the  following'  treatment,  of  the  subject  the  descri])tion  and  analysis 
of  the  elements  of  shore  topography  will  be  followed  by  a  comparison  of 
certain  of  these  elements  with  sinuilating  features  of  ditferent  origin.  First, 
however,  a  few  words  will  be  devoted  to  the  consideration  of  shore  shaping 
as  a  di\'ision  of  the  more  general  process  of  earth  shaping. 

The  earth  owes  its  spheroidal  form  to  gravity  and  rotation.  It  owes 
its  o-reat  features  of  continent  and  ocean  bed  to  the  mieciual  distribution  of 
the  heterogeneous  material  of  which  it  is  composed.  Many  of  its  minor 
inequalities  can  be  referred  to  the  same  cause,  but  its  details  of  siu'face  are 
chiefly  molded  by  the  circulation  of  the  fluids  which  envelope  it.  This 
shaping  or  molding  of  the  surface  may  be  divided  into  three  parts — sul)- 
aerial  shaping  (land  sculpture),  subaqueous  shaping,  and  littoral  shaping. 
In  each  case  the  process  is  threefold,  comprising  erosion,  transportation,  and 
deposition. 

In  subaerial  or  land  shaping  the  agents  of  erosion  are  meteoric — rain, 
acting  both  mechanically  and  chemically,  streams,  and  frost.  The  agent  of 
transportation  is  running  water.  The  condition  of  deposition  is  diminishing 
velocity. 

In  subaqueous  shaping,  or  the  molding  of  surface  which  takes  })lace 
beneath  lakes  and  oceans,  currents  constitute  the  agent  of  erosion.  They 
constitute  also  the  agent  of  transportation;  and  the  condition  of  deposition 
is,  as  before,  dimiiaishing  velocity. 

In  littoral  shapings  or  the  modeling-  of  shore  features,  waves  constitute 
the  agent  of  erosion.  Transportation  is  performed  by  waves  and  cuiTents 
acting  conjointly,  and  the  condition  of  deposition  is  increasing  depth. 

On  the  land  the  amount  of  erosion  vastly  exceeds  the  amount  of  dep- 
osition. Under  standing  water  erosion  is  either  nil  or  incomj)arably  inferior 
in  amoiint  to  deposition.  And  these  two  facts  are  correlatives,  since  the 
product  of  land  erosion  is  chiefly  deposited  in  lakes  and  oceans,  and  the 
sediments  of  lakes  and  oceans  are  derived  chiefly  from  land  erosion.  The 
products  of  littoral  erosion  undergo  division,  going  partly  to  littoral  dep- 
osition and  partly  to  subaqueous  deposition.  The  material  for  littoral 
deposition  is  derived  partly  from  littoral  erosion  and  partly  from  land 
erosion. 


28  LAKE  BONNEVILLE. 

That  is  to  say,  the  detritus  worn  from  the  land  by  meteoric  agents  is 
transported  outward  by  streams.  Normally  it  is  all  carried  to  the  coast,  but 
owing  to  the  almost  universal  complication  of  erosion  with  local  uplift,  there 
is  a  certain  share  of  detritus  dep<isited  upon  the  basins  jind  lower  slopes  of 
the  land.  At  the  shore  a  second  <li\isi()n  takes  place,  the  smaller  portion 
being  arrested  and  l)uilt  into  various  shore  structures,  while  the  larger  por- 
tion continues  outwnrd  and  is  deposited  in  tlic  sen  or  lake.  The  product  of 
shore  erosion  is  similarly  divided.  A  part  remains  upon  the  slntre,  wliere  it 
is  combined  wilh  material  derived  from  the  hnid,  and  the  remainder  goes  to 
swell  the  volume  of  subac^ueous  deposition. 

The  forms  of  the  land  are  given  chiefly  by  erosion.  Since  the  wear 
by  streams  keeps  necessarily  in  advance  of  the  waste  of  the  intervening 
surfaces,  and  since,  also,  there  is  inequality  of  erosion  dependent  on  diver- 
sity of  texture,  land  forms  are  characterized  by  their  variety. 

The  forms  of  sea  beds  and  lake  beds  are  given  by  deposition.  The 
great  currents  by  which  subaqueous  sediments  are  distributed  swee^)  over 
the  ridges  and  other  prominences  of  the  surface  and  leave  the  intervening  de- 
pressions comparatively  currentless.  Deposition,  depending  on  retardation 
of  current,  takes  place  chiefly  in  the  depressions,  so  that  they  are  eventually 
filled  and  a  monotonous  uniformity  is  the  result. 

The  forms  of  the  shore  are  intermediate  in  point  of  variety  between 
those  of  the  land  and  those  of  the  sea  bed;  and  since  they  alone  claim 
parentage  in  waves,  they  are  sui  generis. 

Ocean  shores  are  genetically  distinguished  from  lake  .shores  by  the 
cooperation  of  tides,  which  modify  the  work  accomjilLshed  by  waves  and 
wind  currents. 

The  phenomena  of  ocean  shores  are  therefore  more  complicated  than 
those  of  lake  shores,  and  an  exhaustive  treatment  of  the  subject  would 
include  the  discussion  of  their  distinjiuishino-  characteristics,  l^hev  fall, 
however,  without  the  limits  of  the  present  investigation,  and  in  the  analysis 
which  follows,  the  influence  of  tides  is  not  considered.  It  is  perhaps  to  be 
regretted  that  the  systematic  treatment  here  jiroposed  could  not  be  so 
extended  as  to  include  all  shores,  but  there;  is  a  cei'tain  compensation  in  the 
fact  that  the  results  reached  in  reference  to  lake  shores  have  an  important 


SEA  SHORES  AND  LAKE  SHORES.  29 

neo-ative  becaring  on  tidal  discussions.  It  was  long  ago  pointed  out  by 
Beaumont^  and  Desor^  that  many  of  the  more  important  features  ascribed 
by  hydraulic  engineers  to  tidal  action,  are  produced  on  the  shores  of  inland 
seas  liy  waves  alone;  and  the  demonstration  of  wave  work  pure  and  simple 
should  be  serviceable  to  the  maritime  engineer  by  pointing  out  those  results 
in  explanation  of  which  it  is  unnecessary  to  appeal  to  the  agency  of  tides. 
The  order  of  treatment  is  based  on  the  three-fold  division  of  the  proc- 
ess of  shore  shaping.  Littoral  erosion  and  the  origin  of  the  sea-cliff  and 
wave-cut  terrace  will  be  first  explained,  then  the  process  of  littoral  trans- 
portation with  its  dependent  features,  the  beach  and  the  barrier,  and  finally 
the  process  of  littoral  deposition,  resulting  in  the  embankment,  with  all  its 
varied  phases,  and  the  delta. 

WAVE  WORK. 

LITTORAL  EROSION. 

In  shore  sculpture  the  agent  of  erosion  is  the  wave.  All  varieties  of 
wave  motion  which  aff'ect  standing  water  are  susceptible  of  producing  ero- 
sive eff"ect  on  the  shore,  but  only  those  set  in  motion  by  wind  need  be  con- 
sidered here.  They  are  of  two  kinds:  the  wind  wave  proper,  which  exists 
only  during  the  continuance  of  the  wind;  and  the  swell,  which  continues 
after  the  wind  has  ceased.  It  is  unnecessary  to  discriminate  the  effects  of 
these  upon  the  shore  further  than  to  say  that  the  wind  wave  is  the  more 
efficient  and  therefore  the  better  deserving  of  special  consideration.  In  the 
wind  wave  two  things  move  forward,  the  undulation  and  the  water.  The 
velocity  of  the  undulation  is  relatively  rapid;  that  of  the  water  is  slow  and 
rhythmic.  A  particle  of  water  at  or  near  the  surface,  as  each  undulation 
passes,  describes  an  orbit  in  a  vertical  })lane,  but  does  not  return  to  the 
starting  point.  While  on  the  crest  of  the  wave  it  moves  forward,  and  while 
in  the  trough  it  moves  less  rapidly  backward,  so  that  there  is  a  residual 
advance.' 

'  Lefons  ile  gdologie  pratique,  vol.  1,  p.  232. 

"^  E.  Uesor,  Geology  of  Lake  Superior  Land  District  by  Foster  &  Whitney,  Washington,  1851, 
vol.  2,  pp.  2fi2,  266. 

^The  theory  of  wave  motion  involved  in  this  and  the  following  paragraphs  is  based  partly  on 
observation  but  chiefly  on  the  discussions  of  J.  S.  Russell,  Airy,  Cialdi,  and  Rankine. 


30  LAKE  BONNEVILLE. 

This  residual  advance  is  the  initiatory  element  of  current.  By  virtue 
of  it  the  upper  layer  of  water  is  carried  forward  with  i-eference  to  the  layer 
below,  being  given  a  differential  movement  in  the  direction  towards  which 
the  wind  blows.  This  movement  is  gi'adually  propagated  to  lo^ver  aqueous 
strata,  and  ultimately  produces  movement  of  the  whole  body,  or  a  wind- 
wrought  current.  So  long  as  the  velocity  of  the  wind  remains  constant,  the 
velocity  of  the  current  is  less  than  that  of  the  wind;  and  there  is  always  a 
differential  movement  of  the  water,  each  layer  moving  faster  than  the  one 
beneath.  The  friction  is  thus  distril)uted  through  the  whole  vertical  column, 
and  is  even  borne  in  part  liy  the  lake  bottom.  The  greater  the  depth  the 
smaller  the  share  of  friction  a})portioiied  to  each  layer  of  water  and  the 
greater  the  velocity  of  current  which  can  be  communicated  Ijy  a  given  wind.* 
The  height  of  waves  is  likewise  conditioned  by  depth  of  water,  deep  water 
permitting  the  formation  of  those  that  are  relatively  large. 

When  the  wave  approaches  a  shelving  shore  its  habit  is  changed.  The 
velocity  of  the  undulation  is  diminished,  while  the  velocity  of  the  advancing 
particles  of  Avater  in  the  crest  is  increased;  the  wavelength,  measured  from 
trough  to  trough,  is  diminished,  and  the  wave  height  is  increased;  the  crest 
becomes  acute,  with  the  front  steeper  than  the  back;  and  these  changes 
culminate  in  the  breaking  of  the  crest,  when  the  undulation  proper  ceases. 
The  return  of  the  water  thrown  forward  in  the  crest  is  accomplished  by  a 
current  along  the  bottom  called  the  undertow.  The  momentum  of  the 
advancing  water  contained  in  the  wave  crest  gives  to  it  its  power  of  erosion. 
The  undertow  is  efficient  in  i-emoving  the  products  of  erosion. 

The  retardation  of  the  undulation  by  diminishing  de])t]i  <  if  water  I'lianges 
the  direction  of  its  axis  or  crest  line — excepting  when  the  axis  is  parallel  to 
the  contours  of  the  shoaling  bottom — and  the  phenomena  are  analogous  to 
those  of  the  refraction  of  light  and  sound.  As  a,  wave  passes  obliquely 
from  deej)  water  to  a  broad  shoal  of  iniiform  depth,  the  end  first  entering 
shoal  water  is  first  retarded  and  the  crest  line  is  for  the  moment  bent.  When 
the  entire  crest  has  reached  shoal  water  it  is  once  more  straight,  but  with  a 
new  trend,  a  trend  making  a  narrower  angle  with  the  line  of  sejiaration 

'  This  is  a  matter  of  observation  rather  than  theory.     It  implies  that  the  friction  between  con- 
tiguous films  of  water  increases  iu  more  than  simple  ratio  with  the  differential  velocity  of  the  films. 


REFRACTION  OF  WIND  WAVES.  31 

between  deep  and  shallow  water.  The  wave  has  been  i-efracted.  When  a 
wave  passes  obliquely  from  deep  water  to  shoal  water  whose  bottom  grad- 
ually rises  to  a  shore,  the  end  nearer  the  shore  is  the  more  retarded  at  all 
stages  of  progress  and  the  crest  line  is  continuously  curved.  When  the 
wave  breaks  and  the  inidulation  ceases,  the  crest  line  is  nearly  parallel  to 
the  shore.  It  results  that  for  a  wide  range  of  wind  direction  there  is  but 
small  rauffe  in  the  direction  of  wave  trend  at  the  shore.  It  results  also,  as 
has  been  often  noted,  that  Avhen  the  wind  blows  ncirmally  into  a  circling 
bay,  the  waves  it  brings  are  diversely  turned,  so  as  to  beat  against  both 
sides  as  well  as  the  head  of  the  bay. 

When  the  land  at  the  margin  of  the  water  consists  of  unconsolidated 
material  or  of  fragmental  matter  lightly  cemented,  the  simple  impact  of  the 
water  is  sufficient  to  displace  or  erode  it.  The  same  force  is  competent  also 
to  disintegrate  and  remove  firmer  rock  that  has  been  superficially  weakened 
by  frost  or  is  partially  divided  by  cracks,  but  it  may  be  doubted  whether  it 
has  any  power  to  wear  rock  that  is  thoroughly  coherent.  The  impact  of 
large  waves  has  great  force,  and  its  statement  in  tons  to  the  square  foot  is 
most  impressive;  but,  so  far  as  our  observation  has  extended,  the  erosive 
action  of  waves  of  clear  water  beating  upon  firm  rock  without  seams  is  prac- 
tically nil.  On  the  shores  of  Lake  Bonneville,  not  only  was  there  no  erosion 
on  the  faces  of  cliffs  at  points  where  the  waves  carried  no  detrital  fragments, 
but  there  was  actually  deposition  of  calcareous  tufa;  and  this  deposition  was 
most  rapid  at  points  specially  exposed  to  the  violence  of  the  waves. 

The  case  is  very  different  when  the  rock  is  divided  by  seams,  for  then 
the  principle  of  the  hydrostatic  press  finds  ap])lication.  Through  the  water 
forced  into  the  seams,  and  sometimes  through  air  imprisoned  and  compressed 
by  the  water,  the  blow  stru(;k  liy  the  wave  is  applied  not  merely  to  large 
surfaces  but  in  directions  favorable  to  the  reiidino-  and  dislocation  of  rock 
masses. 

It  rarely  happens,  however,  that  the  impact  of  waves  is  not  reinforced 
by  the  impact  of  mineral  matter  borne  by  them.  The  detritus  worn  from 
the  shore  is  always  at  hand  to  be  used  by  the  waves  in  continuance  of  the 
attack;  and  to  this  is  added  other  detritus  carried  along  the  shore  by  a  pro- 
cess presently  to  be  described. 


32  LAKE  BONNEVILLE. 

The  rock  frari^-ments  which  constitute  the  tool  of  erosion  are  themselves 
worn  and  comminuted  by  use  until  they  become  so  fine  tliat  they  no  longer 
lie  in  the  zone  of  breakers  but  are  carried  away  by  the  undertow. 

The  direct  work  of  wave  erosion  is  restricted  to  a  horizontal  zone  de- 
pendent on  tlie  heiylit  of  the  waves.  There  is  no  impact  of  breakers  at  levels 
lower  than  i\w  troughs  of  the  waves;  and  the  most  efficient  impact  is  limited 
upward  l)y  the  level  of  the  wave  crests,  although  the  dashing  of  the  water 
produces  feebler  blows  at  higher  levels.  Tlie  indirect  work  has  no  suj)erior 
limit,  for  as  the  excavation  of  the  zone  is  carried  landward,  masses  higher 
up  on  the  slope  are  sapped  so  as  to  break  away  and  fall  b}'  mere  gravity. 
Being  thus  brought  within  reach  of  the  waves,  they  are  then  broken  up  by 
them,  retarding  the  zonal  excavation  for  a  time  but  eventually  adding  to  the 
tool  of  erosion  in  a  way  that  partially  compensates. 

Let  us  now  consider  what  goes  on  beneath  the  surface  of  the  water. 
Tlie  agitation  of  which  waves  are  the  superficial  manifestation  is  not  re- 
stricted to  their  horizon,  but  is  propagated  indefinitely  downward.  Near 
the  surface  the  amount  of  motion  diminishes  rapidly  downward,  but  the  rate 
of  diminution  itself  diminishes,  and  there  seems  no  theoretic  reason  for  as- 
signing any  limit  to  the  propagation  of  the  oscillation.  Indeed,  the  agitation 
must  be  carried  to  the  bottom  in  all  cases  where  the  depth  operates  as  a 
condition  in  determining  the  magnitude  of  waves,  for  that  determination 
can  be  assigned  only  to  a  resistance  opposed  by  the  bottom  to  the  undula- 
tion of  the  water. 

During  the  passage  of  a  wave  each  particle  of  water  affected  by  it  rises 
and  falls,  and  moves  forward  and  backward,  describing  an  orbit.  If  the 
passing  wave  is  a  swell,  the  orbit  of  the  ])article  is  closed,^  and  is  either  a 
circle  or  an  elli[)se;  but  in  the  case  of  a  wind  wave  the  orbit  is  not  closed. 
The  relative  amounts  of  horizontal  and  vertical  motion  depend  on  the  depth 
of  the  particle  beneath  the  surface,  and  <in  the  relation  of  the  total  de})th  of 
the  water  to  the  size  of  the  wave.  If  the  water  is  deep  as  comj)ared  to  the 
wave-length,  the  horizontal  and  vertical  movements  are  sensibly  equal,  and 
their  amount  diminishes  rapidly  from  the  surface  downward.     If  the  depth 

'This  is  strictly  true  only  while  the  swell  tr.averses  deep  water.  It  is  pointed  out  by  Cialdi  that 
in  passiiij;  to  shoal  water  the  swell  is  converted  into  a  wave  of  translation,  and  the  particles  no  longer 
return  to  their  points  of  starting. 


PULSATION  OF  THE  UNDIilHTOW.  33 

is  small,  the  liorizontal  motion  is  greater  than  the  vertical,  but  diminishes 
less  rapidly  with  dei)tli.  Near  the  line  of  breakers,  the  vertical  motion  close 
to  the  bottom  becomes  inap})reciable,  while  the  horizontal  oscillation  is 
nearly  as  great  as  at  the  surface.  This  horizontal  motion,  affecting  water 
which  is  at  the  same  time  under  the  influence  of  the  undertow,  gives  to  that 
current  a  pulsating  character,  and  thus  endows  it  with  a  higher  transporting 
power  than  would  pertain  to  its  mean  velocity.  Near  the  breaker  line,  the 
oscillation  communicated  by  the  wave  may  even  overcome  and  momentarily 
reverse  the  movement  of  the  undertow.  Inside  the  breg-ker  line  no  oscilla- 
tion proper  is  communicated.  The  broken  Avave  crest,  dashiilg  forward, 
overcomes  the  undertow  and  throws  it  back;  but  the  water  returns  without 
acceleration  as  a  simple  current  descending  a  slo})e. 

It  should  be  explained  that  the  increment  given  by  pulsation  to  the 
transporting  power  of  the  undei'tow  depends  upon  the  general  law  that  the 
transporting  power  of  a  current  is  an  increasing  geometric  function  of  its 
velocity.  Doubling  the  velocity  of  a  current  more  than  doubles  the  amount 
it  can  carry,  and  more  than  doubles  the  size  of  the  particles  it  is  able  to 
move. 

The  transporting  power  of  the  undertow  diminishes  rapidly  from  the 
breaker  line  outward.  That  part  of  its  power  which  depends  on  its  mean 
velocity  diminishes  as  the  prism  of  the  undertow  increases;  that  j)art  which 
depends  on  the  rhythmic  accelerations  of  velocity  diminishes  as  the  depth  of 
water  increases. 

The  pulsating  current  of  the  undertow  has  an  erosive  as  well  as  a 
transporting  function.  It  carries  to  and  fro  the  detritus  of  the  shore,  and, 
dragging  it  over  the  bottom,  continues  downward  the  erosion  initiated  by 
the  breakers.  This  downward  erosion  is  the  necessary  concomitant  of  the 
shoreward  progress  of  wave  erosion;  for  if  the  land  were  merely  planed 
away  to  the  level  of  the  wave  troughs,  the  incoming  waves  would  break 
where  shoal  water  was  first  reached  and  become  ineffective  at  the  water 
margin.  In  feet,  this  spending  of  the  force  of  the  waves  where  the  water  is 
so  shallow  as  to  induce  them  to  break,  increases  at  that  point  the  erosive 
power  by  pulsation,  and  thus  brings  about  an  interdependence  of  parts. 
What  may  be  called  a  normal  profile  of  the  submerged  terrace  is  produced, 

MON — VOL   I 3 


34  LAKE  BONNEVILLE. 

the  parts  of  which  are  adjusted  to  a  harmonious  interrelation.  If  some 
exceptional  temporary  condition  ])roduces  abnormal  wearing  of  the  outer 
margin  of  the  terrace,  the  greater  deptli  of  water  at  that  point  jjermits  the 
incoming  waves  to  pass  with  little  impediment  and  perfonn  their  work  of 
erosion  upon  jjortions  nearer  the  shore,  thus  restoring  the  equilibrium.  If 
exceptional  resistance  is  opposed  by  the  material  at  the  water  margin,  ero- 
sion is  there  retarded  until  the  submerged  terrace  has  been  so  reduced  as  to 
permit  the  incoming  waves  to  attack  the  land  with  a  greater  share  of  unex- 
pended energy.  Conversely,  if  there  is  a  diminution  of  resistance  at  the 
water  margin,  so  as  to  pennit  a  rapid  erosion,  the  landward  recession  of  that 
margin  causes  it  to  be  the  less  exposed  to  wave  action.  Thus  the  landward 
wear  at  the  water  margin  and  the  downward  wear  in  the  several  parts  of 
the  submerged  plateau  are  adjusted  to  an  interdependent  relation. 

The  Sea-Cliff— Wave  crosiou,  acting  along  a  definite  zone,  may  be  rudely 
compared  to  the  operation  of  a  horizontal  saw;  but  the  upper  wall  of  the 
saw  cut,  being  without  support,  is  broken  away  by  its  own  weight  and  falls 
in  fragments,  leaving  a  cliff  at  the  shoreward  margin  of  the  cut.  This  wave- 
wrought  cliff  requires  a  distinctive  name  to  avoid  confusion  with  cliffs  of 
other  origin,  and  might  with  propriety  in  this  discussion  be  called  a  lake-cliff; 
but  the  term  sea-cliff  is  so  well  established  that  it  appears  best  to  retain  it. 

One  of  the  most  noteworthy  and  constant  characters  of  the  sea-cliff  is 
the  horizontality  of  its  base.  Being  determined  by  wave  erosion  the  base 
must  always  stand  at  about  the  level  of  the  lake  on  which  the  waves  are 
fonned.  The  material  of  the  cliff  is  the  material  of  the  land  from  Avhich  it 
is  carved.  Its  declivity  depends  partly  on  the  nature  of  that  material  and 
partly  on  the  rate  of  erosion.  If  the  material  is  unconsolidated,  the  inclina- 
tion cannot  exceed  the  normal  earth  slope;  if  it  is  thoroughly  indurated,  the 
cliff  may  be  vertical  or  may  even  overhang.  If  the  rate  of  wave  erosion  is 
exceedingly  rapid,  the  cliff  is  as  steep  as  the  material  will  permit;  if  the  rate 
is  slow,  the  inclination  is  diminished  by  the  atmospheric  waste  of  the  cliff 
face. 

Figure  1  represents  a  cliff'  on  the  shore  of  Great  Salt  Lake.  The 
material  in  this  case  is  arenaceous  limestone.  At  the  base  of  the  cliff  may 
be  seen  a  portion  of  the  accompanying  wave-cut  teiTace,  and  the  fore- 


SEA-GLIFFS. 


35 


gi-ound  exhibits  a  portion  of  the  associated  beach.  The  hirge  bowlders 
of  tlie  foreground  have  an  independent  origin,  but  the  shingle  and  otlier 
material  of  the  beach  were  derived  from  the  erosion  of  the  cliff  and  trans- 
ported to  their  present  position  by  the  waves.  Sheep  Rock  is  overlooked 
by  the  northern  face  of  the  Oquirrh  mountain  range,  on  which  the  Bonne- 
ville shores  are  traced,  and  the  partial  view  of  the  mountain  face  given  in 
the  frontispiece  shows  a  line  of  ancient  sea-cliffs,  originally  as  precipitous 
as  Sheep  Rock  but  now  shattered  by  frost  and  partially  drajijcd  by  talus. 


Fig.  1.— Sheep  Bock,  a  SeaClilf  on  the  shore  of  Great  Salt  Lake.    From  a  photograph  by  C.  K.  Savage. 


It  will  appear  in  the  sequel  that  the  distribution  of  sea-cliffs  is  some- 
what peculiar,  but  this  cannot  be  described  until  the  process  of  littoral  trans- 
portation has  been  explained. 

Tht  Wave-Cut  Terrace.-The  submcrgcd  plateau  whose  area  records  the  land- 
ward progi-ess  of  littDral  erosion,  becomes  a  terrace  after  the  formative  lake 


36 


LAKE  BONNEVILLE. 


has  disappeared,  and,  as  such,  requires  a  distinctive  name.     It  -will  be  called 
the  wave-cut  terrace. 

Its  prime  characteristics  are,  first,  that  it  is  associated  witli  a  cliti"; 
second,  that  its  upper  margin,  where  it  joins  the  clifF,  is  horizontal;  and, 
third,  that  its  surface  has  a  gentle  inclination  away  from  the  cliff.  There  is 
an  exceptional  case  in  which  an  island  or  a  hill  ot"  the  mainland  has  been 
completely  pared  away  by  wave  action,  so  that  no  cliff  remains  as  a  compan- 
ion for  the  wave-cut  terrace;  but  this  exception  does  not  invalidate  the  nile. 
The  lake  ward  inclination  is  somewhat  variable,  depending  on  the  nature  of 
the  mateiial  and  on  the  pristine  acclivity  of  the  land.  It  is  greater  where 
the  material  is  loose  than  where  it  is  coherent;  and  greater  where  the  ratio 
of  terrace  width  to  cliff  height  is  small.  It  is  probal^ly  conditi(jned  also  by 
the  tlirection  of  the  current  associated  with  the  wind  efficient  in  its  production; 
but  this  has  not  been  definitely  ascertained. 

The  width  of  the  ten-ace  depends  on  the  extent  of  the  littoral  erosion, 
and  is  not  assignable.  Its  relative  width  in  different  parts  of  a  given  con- 
tinuous coast  depends  entirely  on  the  conditions  determining  the  rapidity  of 
erosion,  and  the  discussion  of  these  at  this  point  would  be  premature. 

Sometimes  a  portion  of  the  eroded  material  gathers  at  the  outer  edge 
of  the  terrace,  extending  its  profile  as  indicated  in  Figure  4.^ 

Figi;res  2  and  3  show  ideal  sections  of  cliffs  and  terraces,  carved  in  one 
case  from  soft  material,  in  the  other  from  hard.     The  station  of  the  artist 


Fig.  2.— Section  of  a  Sea  Clifl  and  Cut-Turracn  in 
Incoherent  Material. 


Fig.  3.— Section  of  a  Sea  ClitT  and  Cut-Terrace  in   Hard 
Mnt«rial. 


in  sketching  the  view  represented  in  the  frontispiece  was  on  a  cut-terrace, 
and  a  portion  of  it  appears  in  the  foreground. 

'  I   C.  Russell.     Geological  History  of  Lake  Lahoutau,  p.  S9. 


COOPEliATIOJT  OF  WAVES  AND  CURRENTS.  37 

LITTORAL  TRANSPORTATION. 

Littoral  transportation  is  performed  by  the  joint  action  of  waves  and 
currents.  Usually,  and  especially  when  the  wind  blows,  the  water  adja- 
cent to  the  shore  is  stuTed  by  a  gentle  current  flowing  parallel  to  the  water 
margin.  This  carries  along  the  particles  of  detritus  agitated  by  the  waves. 
The  waves  and  undertow  move  the  shallow  water  near  the  shore  rapidly  to 
and  fro,  and  in  so  doing  momentarily  lift  some  particles,  and  roll  others 
forward  and  back.  The  particles  thus  wholly  or  partially  sustained  by  the 
water  are  at  the  same  moment  carried  in  a  direction  parallel  to  the  shore  by 
the  shore  current.  The  shore  current  is  nearly  always  gentle  and  has  of 
itself  no  power  to  move  detritus. 

When  the  play  of  the  waves  ceases,  all  shore  action  is  arrested.  When 
the  play  of  the  waves  is  unaccompanied  by  a  current,  shore  action  is  nearly 
arrested,  Ijut  not  absolutely.  If  the  incoming  waves  move  in  a  direction 
normal  to  the  shore,  the  advance  and  recoil  of  the  water  move  particles 
toward  and  from  the  shore,  and  effect  no  transfer  in  the  direction  of  the 
shore;  but  if  the  incoming  waves  move  in  an  oblique  direction  the  forward 
transfer  of  particles  is  in  the  direction  of  the  waves,  while  the  backward 
transfer,  by  means  of  the  undertow,  is  sensibly  normal  to  the  shore,  and 
there  is  thus  a  slow  transportation  along  the  shore.  If  there  were  no  cur- 
rents a  great  amount  of  transportation  would  undoubtedly  be  performed  in 
this  way,  but  it  would  be  carried  on  at  a  slow  rate.  The  transporting  effect 
of  waves  alone  is  so  slight  that  only  a  gentle  current  in  the  opposite  direc- 
tion is  necessary  to  counteract  it.  The  concuiTence  of  waves  and  currents 
is  so  general  a  phenomenon,  and  the  ability  of  waves  alone  is  so  small,  that 
the  latter  may  be  disregarded.  The  practical  work  of  transportation  is 
perfoi-med  by  the  conjoint  action  of  waves  and  shore  currents. 

In  the  ocean  the  causes  of  cuiTcnts  are  various.  Besides  wind  currents 
there  are  daily  currents  caused  by  tides  upon  all  coasts,  and  it  is  maintained 
by  some  physicists  that  the  great  currents  are  wholly  or  partly  due  to  the 
unequal  heating  of  the  water  in  different  regions.  But  in  lakes  there  are 
no  appreciable  tides,  and  currents  due  to  unequal  heating  have  never  been 
discriminated.     The  motions  of  the  water  are  controlled  by  the  wind. 


38  LAKE  BONNEVILLE. 

A  long-contimied  wind  in  <ine  direction  produces  a  set  of  currents  har- 
moniously adjusted  to  it.  A  change  in  the  wind  produces  a  change  in  the 
currents,  hut  this  adjustment  is  not  instantaneous,  and  for  a  time  there  is 
lack  of  harmony.  The  strong  winds,  however,  bring  about  an  adjustment 
more  rapidly  than  the  gentle,  and  since  it  is  to  these  that  all  important 
littoral  work  is  ascribed,  the  waves  and  cun-ents  concerned  in  littoral  trans- 
portation may  be  here  regarded  as  depending  on  one  and  the  same  wind. 

A  wind  blowing  directly  toward  a  shore  may  be  conceived  of  as  jjiling 
the  superficial  water  against  the  shore,  to  be  returned  only  by  the  undertow, 
but,  in  fact,  so  simple  a  result  is  rarely  observed.  Usually  there  is  some 
obliquity  of  direction,  in  ^•irtue  of  which  the  shoreward  current  is  partially 
deflected,  so  as  to  produce  as  one  of  its  effects  a  flow  parallel  to  the  shore, 
or  a  littoral  current.  The  littoral  current  thus  tends  in  a  direction  hanno- 
nious  with  the  movement  of  the  waves,  passing  to  the  right  if  the  waves 
tend  in  that  direction,  to  the  left  if  the  waves  tend  thither. 

To  this  rule  there  is  a  noteworthy  exception.  The  undertow  is  not  the 
only  return  current.  It  frequently  occurs  that  part  of  the  water  di-iven 
forward  by  the  wind  returns  as  a  superficial  current  somewhat  opposed  in 
direction  to  tlie  wind.  If  this  cm-rent  follows  a  shore  it  constitutes  a  littoral 
current  whose  tendency  is  opposed  to  that  of  the  waves.  Thus  the  littoral 
current  may  move  to  the  right  while  the  waves  tend  tt  >  the  left,  and  vice  versa. 
In  every  such  case  the  direction  of  transportation  is  the  direction  of  the 
littoral  current. 

The  waves  and  undertow  accomplisli  a  sorting  of  the  detritus.  The 
finer  portion,  being  lifted  up  by  the  agitation  of  the  waves,  is  held  in  sus- 
pension until  carried  outward  to  deep  water  by  the  undertow.  The  coarser 
portion,  sinking  to  the  bottom  more  rapidly,  can  not  be  earned  beyond  the 
zone  of  agitation,  and  remains  as  a  ])art  (tf  the  shore.  Only  the  latter  is 
the  subject  of  littoral  transportation.     It  is  called  tihore  drift. 

With  the  shifting  of  the  wind  the  direction  of  the  littoral  cun'ent  on 
any  lake  shore  is  occasionall}-,  or  it  niay  be  frequently,  reversed,  and  the 
shore  drift  under  its  influence  travels  sometimes  in  one  direction  and  some- 
times in  the  other.  In  most  localities  it  has  a  ])revailing  direction,  not  nec- 
essarily determined  l)y  the  prevailing  direction  of  the  shore  current,  but 


THE  HIGHWAY  OF  THE  SHORE  DRIFT.  39 

rather  by  the  direction  of  that  shore  current  which  accompanies  the  greatest 
waves.  This  is  frequently  but  not  always  the  direction  also  of  the  shore 
current  accomjianing  the  most  violent  storms. 

The  source  of  shore  drift  is  two-fold.  A  large  part  is  derived  from  the 
excavation  of  sea-cliffs,  and  is  thus  the  product  of  littoral  erosion.  From 
every  sea-cliff  a  stream  of  shore  drift  may  be  seen  to  follow  the  coast  in  one 
direction  or  the  other. 

Another  part  is  contributed  by  streams  depositing  at  their  mouths  the 
heavy  part  of  their  detritus,  and  is  more  remotely  derived  from  the  erosion 
of  the  land.  The  smallest  streams  merely  reinforce  the  trains  of  shore  drift 
flowing  from  sea-cliffs,  and  their  tribute  usually  cannot  be  discriminated. 
Larger  streams  furnish  bodies  of  shore  drift  easily  referred  to  their  sources. 
Streams  of  the  first  magnitude,  as  will  be  explained  farther  on,  overwhelm 
the  shore  drift  and  produce  structures  of  an  entirely  different  nature,  known 
as  deltas. 

The  Beach—The  zoue  occupied  by  the  shore  di-ift  in  transit  is  called  the 
heach.     Its  lower  margin  is  beneath  the  water,  a  little  beyond  the  line  where 
the  great  storm  waves  break.     Its  upper  margin  is  usually  a  few  feet  above 
the   level    of  still    water.     Its    profile    is 
steeper  upon  some  shores  than  others,  but 
has  a  general  facies   consonant  with  its 
wave-wrought  origin.     At  each  point  in 
the  i^rofile  the  sloije  represents  an  equilib- 

^  ^  ^  1  Fig.  4.— Section  of  a  Beach. 

rium  in  transjjorting  power  between  the 

inrushing  breaker  and  the  outflowing  undertow.  Where  the  undertow  is 
relatively  potent  its  efficiency  is  diminished  by  a  low  declivity.  •  Where 
the  inward  dash  is  relatively  potent  the  undertow  is  favored  by  a  high  de- 
clivity. The  result  is  a  sigmoid  profile  of  gentle  flexure,  upwardly  convex 
for  a  short  space  near  its  landward  end,  and  concave  beyond. 

In  horizontal  contour  the  beach  follows  the  original  boundary  between 
land  and  lake,  but  does  not  conform  to  its  irregularities.  Small  indentations 
are  filled  with  shore  di'ift,  small  projections  are  cut  away,  and  smooth,  sweep- 
ing curves  are  given  to  the  water  margin  and  to  the  submerged  contours 
within  reach  of  the  breakers. 


40 


LAKE  BONNEVILLE. 


The  lieach  graduates  insensibly  into  the  wave-cut  terrace.  A  cut-terrace 
lying  in  the  route  of  shore  drift  is  alternately  Imried  ^)y  drift  and  swept 
bare,  as  the  conditions  ot  wind  and  breaker  vary.  Tlie  cut-and-built  ter- 
race (Figure  .'')),  which  owes  its  detrital  extension  to  the  agencies  detennin- 

ing  the  beach  profile,  may  be  regarded 
as  a  forai  intermediate  between  the 
beach  and  the  ciit  terrace. 

The  Barrier. -Where  the  sublittoral 
bottom  of  the  lake  has  an  exceedingly 
gentle  inclination  the  waves  break  at  a 
considerable  distance  from  the  water 


Fig.  5.— Section  of  a  Cntand  Built  Terrace. 


margin.     The  most  violent  agitation  of 


Fig.  6. — Section  of  a  Barrier. 


the  water  is  along  the  line  of  breakers;  and  the  shore  di-ift,  depending  upon 
agitation  for  its  transportation,  follows  the  line  of  the  breakers  instead  of 
the  water  margin.  It  is  thus  built  into  a  continuous  outlying  ridge  at  some 
distance  from  the  water's  edge.     It  will  be  convenient  to  speak  of  this  ridge 

as  a  harrier 

The  barrier  is  the  functional  equiva- 
lent of  the  beach.  It  is  the  road  along 
which  shore  drift  travels,  and  it  is  itself 
composed  of  shore  drift.  Its  lakeward 
face  has  the  typical  beach  profile,  and  its  crest  lies  a  few  feet  above  the 
normal  level  of  the  Avater. 

Between  the  barrier  and  the  land  a  strip  of  water  is  inclosed,  consti- 
tuting a  lagoon.  This  is  frequently  converted  into  a  marsh  by  the  accumu- 
lation of  silt  and  vegetable  matter,  and  eventually  becomes  completely  filled, 
so  as  to  bridge  over  the  interval  between  land  and  barrier  and  convert  the 
latter  into  a  normal  beach. 

The  beach  and  the  barrier  are  absolutely  dependent  on  shore  drift  for 
their  existence.  If  the  essential  contiinious  supply  of  moving  detritus  is  cut 
off,  not  only  is  the  structure  demolished  l)y  the  waves  which  formed  it,  but 
the  work  of  excavation  is  carried  landward,  creating  a  wave-cut  teiTace  and 
a  cliff. 

The  principal  elements  of  the  theory  of  shore-drift  deposits  here  set 


GEOMETRIC  RATIO  OP  EFFECT  TO  CAUSE,  41 

forth  are  tacitly  postulated  by  many  writers  on  the  construction  of  harbor 
and  coast  defenses.  According  to  Cialdi'  the  potency  of  currents  in  con- 
nection with  waves  was  first  announced  by  Montanari;  it  has  been  concisely 
and,  so  fixr  as  appears,  independently  elucidated  by  Andrews.^ 

Still  water  level  is  the  datum  with  which  all  vertical  elements  of  the 
profile  of  the  beach  and  barrier  are  necessarily  compared;  and,  referred  to 
this  standard,  not  only  does  the  maximum  height  of  the  beach  or  barrier 
vary  in  thflferent  parts  of  the  same  shore,  liut  the  profile  as  a  whole  stands 
at  different  heights. 

The  explanation  of  these  inequalities  dej)ends  in  part  on  a  principle  of 
wide  application,  which  is  on  the  one  hand  so  important  and  on  the  other  so 
frecpiently  ignored  that  a  paragraph  may  properly  be  devoted  to  it,  by  way 
of  digression.  There  are  numerous  geologic  processes  in  which  quantitative 
variations  of  a  causative  factor  work  immensely  greater  quantitative  varia- 
tions of  the  effect.  It  is  somewhat  as  though  the  effect  was  proportioned  to 
an  algebraic  power  of  the  cause,  but  the  relation  is  never  so  simple.  Take, 
for  example,  the  transportation  of  detritus  by  a  stream.  The  variable  cause 
is  the  volume  of  water;  the  variable  effect  is  the  amount  of  geologic  work 
done — the  quantity  of  detritus  transported.  The  effect  is  related  to  the 
cause  in  three  different  ways:  First,  increase  of  water  volume  augments  the 
velocity  of  flow,  and  with  increase  of  velocity  the  size  of  the  maximmn  parti- 
cle which  can  be  moved  increases  rapidly.  According  to  Hopkins,  the  size 
of  the  maximum  fragment  which  can  be  moved  varies  as  the  sixth  power  of 
the  velocity,  or  (roughly)  as  the  f  power  of  the  volume  of  water.  Second, 
the  increase  of  velocity  enlarges  the  capacity  of  the  water  to  transport  detritus 
of  a  given  character;  that  is,  the  per  cent  of  load  to  the  unit  of  water  is  in- 
creased. Third,  increase  in  the  niunber  of  unit  volumes  of  water  increases 
the  load  pro  rata.  The  suimnation  of  these  three  tendencies  gives  to  the 
flooded  stream  a  transporting  power  scarcely  to  be  compared  with  that  of 
the  same  stream  at  its  low  stage,  and  it  gives  to  the  exceptional  flood  a 

'  Loc.  cit.,  p.  394,  et  seq.  Cialdi  himself  maintains  at  great  length  that  the  work  is  performed  by 
waves,  and  that  the  so-called  shore  current,  a  feeble  peripheral  circulation  observed  in  the  Mediter- 
ranean, is  (jualitatively  and  quantitatively  incompetent  to  jiroduce  the  observed  results.  Whether  he 
would  deny  the  efflciency  of  currents  excited  by  the  same  winds  which  produce  the  waves  is  not  clearly 
apparent 

*■  Trans.  Chicago.  Acad.  Sci.,  vol.  a,  p.  9. 


42  LAKE  BONNEVILLE. 

power  greatly  in  excess  of  the  nomaal  or  annual  flood.  Not  only  is  it  time 
that  the  work  accomplished  in  a  few  days  during'  the  height  of  the  chief  flood 
of  the  year  is  greater  than  all  that  is  accomplished  during  the  remainder  of 
the  year,  but  it  may  even  be  true  that  the  eflect  of  the  maximum  flood  of 
the  decade  ftr  generation  or  century  surpasses  the  combined  efl"ects  of  all 
mmor  floods.  It  follows  that  the  dimensions  of  the  channel  are  established 
by  the  great  flood  and  adjusted  to  its  needs. 

In  littoral  transportation  the  great  storm  bears  the  same  relation  to  the 
minor  storm  and  to  the  fair-weather  breeze.  The  waves  created  by  the 
great  storm  not  only  lift  more  detritus  from  each  unit  of  the  littoral  zone, 
but  they  act  upon  a  broader  zone,  and  they  are  competent  to  move  larger 
masses.  The  currents  which  accompany  them  are  correspondingly  rapid, 
and  carrv  forward  the  augmented  shore  di'ift  at  an  accelerated  rate.  It  fol- 
lows  that  the  habit  of  the  shore,  including  not  only  the  maximum  height  of 
the  beach  line  and  the  height  of  its  profile,  but  the  dimensions  of  the  wave- 
cut  terrace  and  of  various  other  wave  products  presently  to  be  described,  is 
determined  by  and  adjusted  to  the  great  storm. 

It  should  be  said  by  way  of  qualification  that  the  low-tide  stream  and 
the  breeze-lifted  wave  have  a  definite  though  subordinate  influence  on  the 
topographic  configuration.  After  the  great  flood  has  passed  by,  the  shrunken 
stream  works  over  the  finer  debris  in  the  bed  of  the  great  channel,  and  by 
removing  at  one  place  and  adding  at  another  shapes  a  small  channel  adjusted 
to  its  volume.  After  the  great  storm  has  passed  from  the  lake  and  the  storm 
s^vell  has  subsided,  the  smaller  waves  of  fair  weather  construct  a  miniature 
beach  profile  adapted  to  their  size,  superposing  it  on  the  greater  profile. 
This  is  done  by  excavating  shore  drift  along  a  narrow  zone  under  water  and 
throwing  it  up  in  a  narrow  ridge  above  the  still  water  level.  Thus,  as  early 
perceived  by  De  la  Beche^  and, Beaumont,^  it  is  only  for  a  short  time  innne- 
diately  after  the  passage  of  the  great  storm  that  the  beach  profile  is  a  simple 
curve;  it  comes  afterward  to  be  inteiTupted  by  a  series  of  superposed 
ridges  produced  by  storms  of  difl"erent  magnitude. 

Reverting  now  to  the  special  conditions  controlling  tlu;  profiles  of  beach 
or  barrier  at  an  individual  locality,  it  is  evident  that  the  chief  of  these  is  the 

'  Mauu.al  of  Geology,  Pbiladelpliia,  1832,  p.  72.  «  Lefoiis,  p.  22(5  ami  plato  IV. 


THE  FETCH  OF  WAVES,  43 

magnitude  of  the  largest  waves  breaking  there.  The  size  of  the  waves  at 
each  locahty  depends  on  the  force  of  the  wind  and  on  its  direction.  A  wind 
bkiwing  from  the  shore  lakeward  produces  no  waves  on  that  shore.  One 
from  the  opposite  shore  produces  waves  whose  height  is  approximately  pro- 
portional to  the  square  root  of  the  distance  through  which  they  are  propa- 
gated, provided  there  are  no  shoals  to  check  their  ^augmentation.  For  a 
given  force  of  wind,  the  greatest  waves  are  produced  when  the  direction  is 
such  as  to  command  the  broadest  sweep  of  water  before  their  incidence  at 
the  particular  spot,  or  in  the  technical  phrase,  when  the  fetch  is  greatest. 

A  second  factor  is  found  in  the  configuration  of  the  bottom.  Where 
the  off-shore  depth  is  great  the  imdertow  rapidly  returns  the  water  driven 
forward  by  the  wind,  and  there  is  little  accumulation  against  the  shore;  but 
where  the  off-shore  depth  is  small  the  wind  piles  the  water  against  the  shore, 
and  produces  all  shore  features  at  a  relatively  high  level. 

The  Subaqueous  Ridge.-Various  writers  liave  mentioned  low  ridges  of  sand  or 
gravel  running  parallel  to  the  shore  and  entirely  submerged.  As  the  origin 
of  such  ridges  is  not  understood,  they  have  no  fixed  position  in  the  pres- 
ent classification,  and  they  are  placed  next  to  the  barrier  only  because  of 
similarity  of  form.    The  following  description  was  published  by  Desor  in  1 851 : 

An  example  of  tbis  character  occurs  on  the  northern  shore  of  Lake  Michigan,  not 
far  from  the  fish  station  of  Bark  Point  (Pointe  aux  J5corces),  under  the  lee  of  a  prom- 
ontory, designated  on  the  map  as  Point  Patterson.  Here,  the  shore,  after  running  due 
east  and  west  for  some  distance,  bends  abruptly  to  the  northeast.  The  voyageur  com- 
ing from  the  west,  after  having  passed  Point  Patterson,  is  struck  by  the  appearance  of 
several  bands  of  shallow  water,  indicated  by  a  yellowish  tint.  These  bands,  which 
appear  to  start  from  the  extremity  of  the  point,  are  caused  by  subaqueous  ridges, 
which  spread,  fan-like,  to  the  distance  of  nearly  half  a  mile  to  the  east,  being  from 
three  to  ten  yards  wide,  and  from  five  to  ten  feet  above  the  general  bed  of  the  lake,  at 
this  point.  They  are  not  composed,  like  the  flats,  of  fine  sand,  but  of  white  limestone 
pebbles,  derived  from  the  adjacent  ledges,  with  an  admixture  of  granitic  pebbles,  some 
of  which  are  a  foot  in  diameter.  It  is  difficult  to  conceive  of  currents  suificiently 
Ijowerful  to  transport  and  arrange  such  heavy  materials,  and  yet  we  know  of  no  other 
means  by  which  this  aggregation  could  have  been  accomplished. 

These  subaqueous  ridges  afford,  on  a  small  scale,  an  interesting  illustration  of  the 
formation  of  similar  ridges  now  above  water.  If  the  north  coast  of  Lake  Michigan 
were  to  be  raised  only  twenty  feet,  such  a  rise  would  lay  dry  a  wide  belt  of  almost 
level  ground,  on  which  these  ridges  would  appear  conspicuously,  not  unlike  those 
which  occur  on  the  south  shores  of  lakes  Erie  and  Ontario,  and  thus  confirm  the 
views  of  Mr,  Whittlesey,  that  most  of  these  ridges  are  not  ancient  beaches,  but  have 
been  formed  under  water,  by  the  action  of  currents,' 

'  Foster  aud  Whitney's  "  Geology  of  f he  Lake  Superior  Land  District."      Part  2,  p.  258. 


44  LAKE  BONNEVILLE. 

Wliittlesey  describes  no  examples  on  existing  coasts,  but  refers  to  them 
as  familiar  features  and  relegates  to  their  category  numerous  inland  ridges 
associated  with  earlier  water  surfaces  in  the  basins  of  Lakes  Erie,  (Jntario, 
and  Michigan.  He  says  that  "their  composition  is  luiiversally  coarse  water- 
washed  sand  and  fine  gravel",  while  beaches  consist  of  "clean  beach  sand 
and  shingle";  and  alsoJ:hat  beaches  are  distinguished  from  subaqueous  ridges 
by  the  fiict  "that  the  foiTner  are  narrow  and  are  steepest  on  the  lake  side, 
resembling  miniature  terraces."' 

Having  personally  observed  many  of  the  inland  ridges  described  by 
Wliittlesey  and  recognized  them  as  barriers,  having  failed  or  neglected  to 
observe  ridges  of  this  subaqueous  type  in  the  Bonneville  Basin,  and  having 
independent  reason  to  believe  that  the  waters  of  Lakes  Michigan,  Erie,  and 
Ontario  have  recently  advanced  on  their  coasts,  I  leaped  to  the  conclusion 
that  the  ridges  seen  by  Desor  beneath  the  water  of  Lake  Michigan,  as  well 
as  the  subaqueous  ridges  mentioned  without  enumeration  by  Whittlesey, 
were  formed  as  barriers  or  spits  at  the  water  surface  and  were  subsequently 
submerged  by  a  rise  of  the  water.^  In  so  doing-  I  ignored  an  im[)ortant 
observation  by  Andrews,  who,  writing  of  the  beach  at  the  head  of  Lake 
Michigan,  describes  "a  peculiarity  in  the  contour  of  the  deposit,  which  is 
uniform  in  all  the  sand  shores  of  this  part  of  the  coast.  As  you  go  out  into 
the  lake,  the  bottom  gradually  descends  from  the  water  line  to  the  depth  of 
about  five  feet,  when  it  rises  again  as  you  recede  from  the  shore,  and  then 
descends  toward  deep  water,  forming  a  siibaqueous  ridge  or  'bar'  jiarallel 
to  the  beach  and  some  ten  or  twenty  rods  from  the  shore."  ^  It  is  impossible 
to  regard  this  sand  ridge  as  a  beach  or  barrier  sulimerged  by  the  rise  of  the 
lake,  for  it  stands  within  the  zone  of  action  of  storm  waves,  and  no  mole 
of  loose  debris  can  be  assumed  to  successfully  oppose  their  attack.  It  is  to 
be  viewed  rather  as  a  product  of  wave  action,  or  of  wave  and  cuiTent  action, 
under  existing  relations  of  land  and  lake. 

The  subject  is  advanced  by  Russell,  who  visited  the  eastern  shore  of 

Lake  Michigan  in  1884.     He  says: 

Bars  of  anotber  character  are  also  formed  along  lake  margins,  at  some  distance 
from  the  land,  which  agree  in  many  ways  with  true  barrier  bars,  but  differ  in  being 

'  Fresh-water  Glaci.il  Drift  of  the  Northwestern  States.     By  Charles  Whittlesey.     Sniithsoniao 
ContribntioM  No.  197.     W-aHhington,  1S66,  pp.  17,  lit. 

'Fifth  Ann.  Rcpt.  U.  S.  Gool.  Survey,  p.  111.  'Traus.  Chicago  Acad.  Sci.,  vol.  ",  p.  14. 


SUBAQUEOUS  RIDGES.  45 

composed  of  homogeneous,  fine  material,  usually  saud,  and  in  not  reaching  the  lake 
surface. 

The  character  of  structures  of  this  uature  may  be  studied  about  the  shores  of 
Lake  Michigan,  where  they  can  be  traced  continuously  for  hundreds  of  miles.  There 
arc  usually  two,  but  occasionally  three,  distinct  sand  ridges;  the  first  being  about  200 
feet  from  the  land,  the  second  75  or  100  feet  beyond  the  first,  and  the  third,  when 
present,  about  as  far  from  the  second  as  the  second  is  from  the  first.  Soundings  on 
these  ridges  show  that  the  first  has  about  8  feet  of  water  over  it,  and  the  second  usually 
about  I'i;  between,  the  depth  is  from  10  to  14  feet.  From  many  commanding  points, 
as  the  summit  of  Sleeping  Bear  Bluff,  for  example,  these  submerged  ridges  may  be 
traced  distinctly  for  many  miles.  They  follow  all  the  main  curves  of  the  shore,  with- 
out changing  their  character  or  having  their  continuity  broken.  They  occur  in  bays 
as  well  as  about  the  bases  of  promontories,  and  are  always  composed  of  clean,  homo- 
geneous sand,  although  the  adjacent  beach  may  be  composed  of  gravel  and  boulders. 
They  are  not  shore  ridges  submerged  by  a  rise  of  the  lake,  for  the  reason  that  they 
are  in  harmony  with  existing  conditions,  and  are  not  being  eroded  or  becoming  cov- 
ered with  lacustral  sediments. 

In  bars  of  this  character  the  fine  debris  arising  from  the  comminution  of  shore 
drift  appears  to  be  accumulated  in  ridges  along  the  line  where  the  undertow  loses  its 
force;  the  distance  of  these  lines  from  the  land  being  determined  by  the  force  of  the 
storms  that  carried  the  waters  shoreward.  This  is  only  a  suggested  explanation, 
however,  as  the  complete  history  of  these  structures  has  not  been  determined.' 

In  the  survey  of  these  lakes  by  the  U.  S.  Engineers,  numerous  inshore 
soundings  were  made,  and  while  these  do  not  fall  near  enough  together  to 
determine  the  configuration  of  subaqueous  ridges,  they  serve  to  show  whetlier 
the  profile  of  the  bottom  descends  continuously  from  the  beach  lakeward. 
A  study  of  the  original  manuscrij)t  sheets,  which  give  fuller  data  than  the 
published  charts,  discovers  that  bars  sunilar  to  those  described  by  Russell 
occur  along  the  eastern  coast  of  Lake  Michigan  wherever  the  bottom  is  sandy, 
being  most  frequently  detectible  at  a  depth  of  13  feet,  but  ranging  upward 
to  3  feet  and  downward  to  18  feet.  At  the  south  end  of  the  lake  they  are 
not  restricted  to  the  5-foot  zone  indicated  by  Andi-ews,  but  range  to  13  feet. 
A  single  locality  of  occurrence  was  found  on  the  shore  of  Lake  Erie,  but 
none  on  Lake  Ontario. 

These  ridges  constitute  an  exception  to  the.  beach  profile,  and  show  that 
the  theory  of  that  profile  given  above  is  incomplete.  Under  conditions  not 
yet  apparent,  and  in  a  manner  equally  obscure,  there  is  a  rhytlunic  action 
along  a  certain  zone  of  the  bottom.  That  zone  lies  lower  than  the  troudi 
between  the  greatest  storm  waves,  but  the  water  upon  it  is  violently  oscil- 

'Geol.  Hist,  of  Lake  Lahontan.    pp.  92-93. 


46  LAKE  BONNEVILLE. 

lated  by  the  jjassing  waves.  The  same  water  is  translated  hikeward  })y  tlie 
undertow,  and  the  surface  water  above  it  is  transhxted  kindward  by  the  wind, 
while  both  move  with  the  shore  current  parallel  to  the  beach.  The  rhythm 
may  be  assumed  to  arise  from  the  interaction  of  the  oscillation,  the  land- 
ward current,  and  the  undertow. 

LITTORAL  DEPOSITION. 

The  material  deposited  by  shore  processes  is,  first,  shore  tb-ift;  second, 
stream  drift,  or  the  detritus  delivered  at  the  shore  by  tributary  streams 
Increasing  depth  of  water  is  in  each  case  the  condition  of  littoral  deposi- 
tion. The  structures  produced  by  the  deposit  of  shore  drift,  although  some- 
what varied,  have  certain  conmion  features.  They  will  be  treated  under 
the  generic  title  of  embankments.  The  sti-uctures  produced  by  the  dejjosit 
of  stream  drift  are  deltas. 

EMBANKMENTS. 

The  current  occupying  the  zone  of  the  shore  drift  and  acting  as  the 
coagent  of  littoral  transportation  has  been  described  as  slow,  but  it  is  insepa- 
rably connected  with  a  movement  that  is  relatively  rapid.  This  latter,  which 
may  be  called  the  off-shore  current,  occupies  deeper  water  and  is  less  impeded 
by  friction.  It  may  in  some  sense  be  said  to  drag  the  littoral  current  along 
with  it.  The  momentum  of  the  off-shore  current  does  not  permit  it  to  fol- 
low the  sinuosities  of  the  water  margin,  and  it  sweeps  from  point  to  point, 
carrying  the  littoral  current  with  it.  There  is  even  a  tendency  to  generate 
eddies  or  return  currents  in  embayments  of  the  coast.  The  off-shore  cur- 
rent is  moreover  controlled  in  part  by  the  configuration  of  the  bottom  and 
by  the  necessity  of  a  return  current.  The  littoral  current,  being  controlled 
in  large  part  by  the  movements  of  the  off-shore  current,  separates  from  the 
water  margin  in  three  ways:  first,  it  continues  its  direction  unchanged  at 
points  where  the  shore-line  turns  landward,  as  at  the  entrances  of  Ijays;  sec- 
ond, it  sometimes  turns  from  the  land  as  a  surface  current;  third,  it  some- 
times descends  and  leaves  the  water  margin  as  a  bottom  cun-ent. 

In  each  of  these  three  cases  deposition  of  shore  di-ift  takes  place  by 
reason  of  the  divorce  of  shore  cuirents  and  wave  action.     The  depth  to 


THE  GENESIS  OF  SPITS.  47 

which  wave  agitation  sufficient  for  the  transportation  of  shore  di-ift  extends 
is  small,  and  when  the  littoral  current  by  leaving  the  shore  passes  into 
deeper  waters  the  shore  di-ift,  unable  to  follow,  is  thrown  down. 

When  the  current  holds  its  direction  and  the  shore-line  diverges,  the 
embankment  takes  the  form  of  a  S2nt,  a  Jiook,  a  hat;  or  a  loop.  When  the 
shore-line  holds  its  course  and  the  current  diverges,  whether  superficially 
or  by  descent,  the  embankment  usually  takes  the  form  of  a  terrace. 

The  spit.-When  a  coast  line  followed  by  a  littoral  current  turns  abruptly 
landward,  as  at  the  entrance  of  a  bay,  the  current  does  not  turn  with  it,  but 
holds  its  course  and  passes  from  shallow  to  deeper  water.  The  water  be- 
tween the  diverging  current  and  coast  is  relatively  still,  although  there  is 
communicated  to  the  portion  adjacent  to  the  current  a  slow  motion  in  the 
same  direction.  The  waves  are  propagated  indifferently  through  the  flow- 
ing and  the  standing  water,  and  reach  the  coast  at  all  points.  The  shore 
drift  can  not  follow  the  deflected  coast  line,  because  the  waves  that  beat 
against  it  av^  unaccompanied  by  a  littoral  current.  It  can  not  follow  the 
littoral  current  into  dee^)  water,  because  at  the  bottom  of  the  deep  water 
there  is  not  sufficient  agitation  to  luove  it.  It  therefore  stops.  But  the 
supply  of  shore  di-ift  brought  to  tliis  point  by  the  littoral  current  does  not 
cease,  and  the  necessary  result  is  accumulation.  The  particles  are  carried 
forward  to  the  edge  of  the  deep  water  and  there  let  fall. 

In  this  way  an  embankment  is  constructed,  and  so  far  as  it  is  built  it 
serves  as  a  road  for  the  transportation  of  more  shore  di'ift.  The  direction 
in  which  it  is  built  is  that  of  the  littoral  current.  It  takes  the  form  of  a 
ridge  following  the  boundary  between  the  current  and  the  still  water.  Its 
initial  height  brings  it  just  near  enough  to  the  surface  of  the  water  to  enable 
the  wave  agitation  to  move  the  particles  of  which  it  is  constructed;  and  it 
is  naiTOw.  But  these  characters  are  not  long  maintained.  The  causes 
which  lead  to  the  consti'uction  of  the  beach  and  the  barrier  are  here  equally 
efficient,  and  cause  the  embankment  to  grow  in  breadth  and  in  height  until 
the  cross-profile  of  its  upper  surface  is  identical  with  that  of  the  beach. 

The  history  of  its  growth  is  readily  deduced  from  the  configuration  of 
its  terminus,  for  the  process  of  growth  is  there  in  progress.  If  the  material 
is  coarse  the  distal  portion  is  very  slightly  submerged,  and  is  terminated  in 


48  LAKE  BONNEVILLE. 

the  direction  of  o^rowtli  by  a  steep  slope,  the  suliaqueous  "earth-sh)pe"  of  the 
particular  material.  If  the  material  is  fine  the  distal  ])ortioii  is  more  deeply 
submerg-ed,  and  is  not  so  abru])tly  tenuinated.  The  portion  above  water 
is  usually  narrow  throughout,  and  terminates  without  reaching  the  extrem- 
ity of  the  embankment.  It  is  flanked  on  the  lakeward  side  by  a  submerged 
plateau,  at  the  outer  edge  of  which  the  descent  is  somewhat  steep.  The 
profile  of  the  plateau  is  that  normal  to  the  beach,  and  its  contours  are  con- 
fluent with  those  of  the  beach  or  barrier  on  the  main  shore.  Toward  the 
end  of  the  embankment  its  width  diminishes,  its  outer  and  limiting  contour 
turning  toward  the  crest  line  of  the  spit  and  finally  joining  it  at  the  sub- 
merged extremity. 

The  process  of  construction  is  similar  to  that  of  a  railroad  embankment 
the  material  for  which  is  derived  from  an  adjacent  cutting,  carted  forward 
along  the  crest  of  the  embanlcment  and  dumped  off  at  the  end;  and  the  sym- 
metry of  form  is  often  more  perfect  than  the  railway  engineer  ever  accom- 
plishes. The  resemblance  to  railway  structures  is  very  striking  in  the  case 
of  the  shores  of  extinct  lakes. 

As  the  embankment  is  carried  forward  and  completed,  contact  between 
the  current  and  the  inshore  water  is  at  first  obstructed  and  finally  cut  off", 
so  that  there  is  practically  no  communication  of  movement  from  one  to  the 
other  at  the  extremity  of  the  spit.  At  the  point  of  construction  the  mo^^ng 
and  the  standing  water  are  sharply  differentiated,  and  there  is  hence  no 
uncertainty  as  to  the  direction  of  construction.  The  spit  not  only  follows 
the  line  between  the  current  and  still  water,  but  aids  in  giving  definition 
to  that  line,  and  eventually  walls  in  the  current  by  contours  adjusted  to  its 
natui'al  flow. 

The  Bar._If  flic  curreut  determining  the  foraiation  of  a  spit  again  touches 
the  shore,  the  construction  of  the  embankment  is  continued  imtil  it  spans 
the  entire  interval.  So  long  as  one  end  remains  free  the  vernacular  of  the 
coast  calls  it  a  spit;  but  when  it  is  completed  it  becomes  a  lar.  Figure  7 
gives  an  ideal  cross-section  of  a  completed  embankment. 

The  bar  has  all  the  characters  of  the  spit  except  those  of  the  tenninal 
end.  Its  cross-profile  shows  a  })lateau  bounded  on  either  hand  by  a  steep 
slope.     The  surface  of  the  plateau  is  not  level,  but  has  the  beach  profile,  is 


BAKS  AT  THE  MOUTHS  OF  KIVEES.  49 

slightly  submerged  on  the  windward  side  and  rises  somewhat  above  the 
ordinary  water  level  at  the  leeward  margin.     At  each  end  it  is  continuous 
with  a  beach    or   bairier.      It   receives 
shore  drift  at  one  end  and  delivers  it  at 
the  other. 

The  bar  may  connect  an  island  with 

the     shore    or    with     another     island,    or    it  Fig.  7.-Section  of  a  Lluear  Kmbanknaut. 

may  connect  two  portions  of  the  same 

shore.  In  the  last  case  it  crosses  the  mouth  either  of  a  bay  or  of  a  river. 
If  maintained  entire  across  the  entrance  to  a  bay  it  converts  the  water  be- 
tween it  and  the  shore  into  a  lagoon.  At  the  mouth  of  a  river  its  mainte- 
nance is  antagonized  by  the  outflowing  current,  and  if  its  integrity  is  estab- 
lished at  all  it  is  only  on  rare  occasions  and  for  a  short  time.  That  is  to 
say,  its  full  height  is  not  maintained;  there  is  no  continuous  exposed  ridge. 
The  shore  di'ift  is,  however,  thrown  into  the  river  cuiTent,  and  unless  that 
current  is  sufficient  to  sweep  it  into  deep  water  a  submerged  bar  is  tlu'own 
across  it,  and  maintains  itself  as  a  partial  obstruction  to  the  flow.  The  site 
of  this  submerged  bar  is  usually  also  the  point  at  which  the  current  of  the 
stream,  meeting  the  standing  water  of  the  lake,  loses  its  velocity  and  depos- 
its the  coarser  paii;  of  its  load  of  detritus.  If  the  contribution  of  river  drift 
greatly  exceeds  that  of  shore  di'ift,  a  delta  is  fomied  at  the  river  mouth,  and 
this,  by  changing  the  configuration  of  the  coast,  modifies  the  littoral  current 
and  usually  detennines  the  shore  drift  to  some  other  course.  If  the  contri- 
bution of  river  drift  is  comparatively  small  it  becomes  a  simple  addition  to 
the  shore  drift,  and  does  not  interrupt  the  continuity  of  its  transportation. 
The  bars  at  the  mouths  of  small  streams  are  constituted  chiefly  of  shore  drift, 
and  all  their  characters  are  determined  by  their  origin.  The  bars  at  the 
mouths  of  large  streams  are  constituted  chiefly  of  stream  di-ift,  and  belong 
to  the  phenomena  of  deltas. 

On  a  preceding  page  the  fact  was  noted  that  the  horizontal  contoiu's  of 
a  beach  are  more  regular  than  those  of  the  original  surface  against  which 
it  rests,  small  depressions  being  filled.  It  is  now  evident  that  the  process  of 
filling  these  is  identical  with  that  of  bar  construction.  There  is  no  trenchant 
line  of  demarkation  between  the  beach  and  the  bar.     Each  is  a  carrier  of 

MON  I 4 


50 


LAKE  BONNEVILLE. 


shore  drift,  and  each  employs  its  first  load  in  the  construction  of  a  suitable 
road. 

Plate  IV  represents  a  part  of  the  east  shore  of  Lake  ]\Iichigan  seen 
from  the  hill  back  of  Empire  liluflfs.  In  the  extreme  distance  at  the  left 
stand  the  Sleeping  Bear  Blutl's,  and  somewhat  nearer  on  the  shore  is  a  tim- 
bered hill,  the  lakeward  face  of  which  is  likewise  a  sea-cliff.  A  bar  coimects 
the  latter  with  the  land  in  the  foreground  and  divides  the  lagoon  at  the  right 
from  the  lake  at  the  left.  The  symmetry  of  the  bar  is  marred  l)y  tlie  for- 
mation of  dunes,  the  li<^ter  portion  of  the  shore-drift  being  taken  ui)  by 
the  wind  and  carried  toward  the  right  so  as  to  initiate  the  filling  of  the 
lagoon. 

Figure  8  is  copied  from  the  U .  S.  Engineer  map  of  a  portion  of  the  south 
shore  of  Lake  Ontario  west  of  the  mouth  of  the  Genesee  River.     The  orig- 


FiG.  8. — Map  of  Braddook'B  Bay  and  vicinity,  N.  T.,  showing  headlands  conneoted  by  Bars. 

inal  contour  of  the  shore  was  there  irregular,  consisting  of  a  series  of  salient 
and  reentrant  angles.  The  waves  have  truncated  some  of  the  salients  and 
have  united  them  all  by  a  continuous  bar,  behind  which  several  bays  or 


/ 


BARS  ACROSS  BATS. 


51 


ponds  are  inclosed.  The  movement  of  the  shore  drift  is  in  this  case  from 
northwest  to  southeast,  and  the  principal  source  of  the  material  is  a  point  of 
land  at  the  extreme  west,  where  a  low  cliff  shows  that  the  land  is  being 
eaten  by  the  Avaves. 

The  map  in  Figure  d  is  also  copied  from  one  of  the  sheets  published 
by  the  U.  8.  Engineers,  and  represents  the  bars  at  the  head  of  'Lake  Supe- 
rior. These  illustrate  several 
elements  of  the  preceding  dis- 
cussion. In  the  first  place  they 
are  not  formed  by  the  predomi- 
nant winds,  bufby  those  which 
brinff  the  greatest  waves.  The 
predominant  winds  are  west- 
erly, and  produce  no  waves  on 
tin  scoast.  The  shore  cWft  is  de- 
rived from  the  south  coast,  and 
its  motion  is  first  westerly  and 
then  northerly.  Two  bars  are 
exhibited,  the  western  of  which 
is  now  protected  from  the  lake 
waves,  and  must  have  been  com- 
pleted before  the  eastern  was 
begun.  The  place  of  deposition  of  shore  drift  was  probably  shifted  from 
the  western  to  the  eastern  by  reason  of  the  shoaling  of  the  head  of  the  lake. 
The  converging  shores  should  theoretically  produce  during  easterly  storms 
a  powerful  undertow,  by  which  a  large  share  of  the  shore  drift  A\'ould  be 
carried  lakeward  and  distributed  over  the  bottom.  The  manner  in  which 
the  bars  terminate  against  the  northern  shore  without  inflection  is  explica- 
ble lilvewise  by  the  theory  of  a  strong  undertow.  If  the  return  current 
*  were  superficial  the  bars  would  be  curved  at  then-  junctions  with  both 
shores. 

An  instructive  view  of  an  ancient  bar  will  be  found  in  PL  IX,  repre- 
senting a  portion  of  the  Bonneville  shore  line.  The  town  of  Stockton,  Utah, 
appears  at  the  right.     The  plain  at  the  left  was  the  bed  of  the  lake-    The 


-■--■  -r- 

Fig.  9.— Map  of  the  head  of  Lake  Superior,  eLowins  Baj  Bars. 


52  LAKE  BONNEVILLE. 

storm  waves,  moving  from  left  to  riglit,  carved  the  sea-cliflP  which  appears 
at  the  base  of  the  mountain  at  the  k^ft,  and  di'ifting  the  material  toward  the 
right  built  it  into  a  great  spit  and  a  greater  bar.  The  end  of  the  s\nt  is 
close  to  the  town.  The  bar,  which  lies  slightly  lower,  having  been  fonned 
by  the  lake  at  a  lower  stage  of  its  water,  sweeps  in  a  broad  curve  across 
the  valley  to  the  rocky  hill  on  the  opposite  side,  where  the  artist  stood  in 
making  the  sketch. 

The  Hook.-Tlie  line  of  direction  followed  by  the  spit  is  usually  straight,  or 
has  a  slight  concavity  toward  the  lake.  This  form  is  a  function  of  the  lit- 
toral current,  to  which  it  owes  origin.  But  that  current  is  not  perpetual;  it 
exists  only  during  the  continuance  of  certain  determining  winds.  Other 
winds,  though  feebler  or  accompanied  by  smaller  waves,  nevertheless  have 
systems  of  currents,  and  these  latter  currents  sometimes  modify  the  form  of 
the  spit.  Winds  which  .simply  reverse  the  du-ection  of  the  littoral  current 
retard  the  construction  of  the  embankment  without  otherwise  affecting  it; 
but  a  cuirent  is  sometimes  made  to  flow  past  the  end  of  the  spit  in  a  direction 
making  a  high  angle  with  its  axis,  and  such  a  current  modifies  its  foim.  It 
cuts  away  a  portion  of  the  extremity  and  rebuilds  the  material  in  a  smaller 
spit  joining  the  main  one  at  an  angle.  If  this  smaller  spit  extends  lake  ward 
it  is  demolished  by  the  next  stonn;  but  if  it  extends  landward  its  position  is 
sheltered,  and  it  remains  a  permanent  feature.  It  not  infi-equently  happens 
that  such  accessory  si)its  are  formed  at  intervals  during  the  construction  of 
a  long  embankment,  and  are  preserved  as  a  series  of  short  branches  on  the 
lee  side. 

It  may  occur  also  that  a  spit  at  a  certain  stage  of  its  growth  becomes 
especially  subject  to  some  conflicting  current,  so  that  its  noimal  gi-owth 
ceases,  and  all  the  shore  drift  transported  along  it  goes  to  the  construction 
of  the  branch.     The  bent  embankment  thus  produced  is  called  a  hook. 

The  currents  efficient  in  the  formation  of  a  hook  do  not  cooi)erate 
simultaneously,  but  exercise  their  functions  in  alternation.  The  one,  during 
the  prevalence  of  certain  winds,  brings  the  shore  drift  to  the  angle  and 
accumulates  it  there;  the  other,  during  the  prevalence  of  other  winds,  de- 
molishes the  new  structure  and  redeposits  the  material  upon  the  other  limb 
of  the  hook. 


HOOKS.  53 

In  case  the  land  on  which  it  is  based  is  a  slender  peninsula  or  a  small 
island,  past  which  the  currents  incited  by  various  winds  sweep  with  little 
modification  of  direction  by  the  local  configuration,  the  hook  no  longer  has 
the  sharp  angle  due  to  the  action  of  two  currents  only,  but  receives  a  curved 
form. 

Hooks  are  of  comparatively  rare  occurrence  on  lake  shores,  but  abound 
at  the  mouths  of  marine  estuaries,  where  littoral  and  tidal  currents  conflict. 

Plate  V  represents  a  recurved  spit  on  the  shore  of  Lake  Michigan,  seen 
from  a  neighboring  bluff.  The  general  direction  of  its  construction  is  from 
left  to  right,  but  storms  from  the  right  have  from  time  to  time  tiu-ned  its  end 
toward  the  land  and  the  successive  recurvements  are  clearly  discernible  near 
the  apex. 

The  mole  enclosing  Toronto  harbor  on  the  shore  of  Lake  Ontario  is  a 
hook  of  unusual  complexity,  and  the  fact  that  its  growth  threatens  to  close 
the  entrance  to  the  harbor  has  led  to  its  thorough  study  by  engineers. 
Especially  has  its  history  been  developed  by  Fleming  in  a  classic  essay  to 
Avhich  reference  has  already  been  made.  A  hill  of  drift  projects  as  a  cape 
from  the  north  shore  of  the  lake.  The  greatest  waves  reaching  it,  those 
having  the  greatest  fetch,  are  from  the  east  (see  Fig.  10),  and  the  cooper- 
ating current  flows  from  east  to  west.  As 
the  hill  gradually  yields  to  the  waves,  its 
coarser  material  trails  westward,  building  a 
spit.  The  waves  and  currents  set  in  mo- 
ti(  >n  by  southwesterly  winds  carry  the  spit 


end  northward,  producing  a  hook.     In  the      ric  lo. -Diagram  of  Lake  Ontario,  to  sbow  tho 


1  -1  J    1  1  ,1  Futch  of  Waves  reaching  Torouto  fiom  (liH'erent 

past  the  westward  movement  has  been  the       directions. 

more  powerful  and  the  spit  has  continued  to  grow  in  that  direction,  its  north- 
ern edge  being  fringed  Avith  the  sand  ridges  due  to  successive  recurvements, 
but  the  shape  of  the  bottom  has  introduced  a  change  of  conditions.  The  water 
at  the  west  end  of  the  spit  is  now  deep,  and  the  extension  of  the  embank- 
ment is  correspondingly  slow.  The  northward  drift,  being  no  longer  sub- 
ject to  frequent  shifting  of  position,  has  cumulative  effect  on  the  terminal 
hook  and  gives  it  a  greater  length  than  the  others.  In  the  chart  of  the  har- 
bor (Fig.  11)  the  composite  character  of  the  mole  is  readily  traced.     It  may 


54 


LAKE    BO]S  NEVILLE. 


also  be  seen  that  the  ends  of  the  successive  hooks  are  connected  by  a  beach, 
the  work  of  waves  generated  within  the  harbor  by  northerly  winds.^  It  will 
be  observed  furthermore  that  while  the  west  end  of  the  spit  is  continuously 
fringed  by  recurved  ridges  its  eastern  part  is  (juite  free  from  them.  This 
does  not  indicate  that  the  spit  was  simple  and  unhooked  in  the  early  stages 
of  growth,  but  that  its  initial  ridge  has  disappeared.     As  the  cliflf  is  eroded. 


Fig.  11. — Map  of  the  harbor  and  peninsula  (Ilook)  at  Toronto.    From  charts  published  by  U.  T.  Hind,  in  1854.* 

its  position  constantly  shifts  landward,  the  shore  current  follows,  and  the 
lakeward  face  of  the  spit  is  carried  away  so  that  the  waves  break  over  it, 
and  then  a  new  crest  is  built  by  the  waves  just  back  of  the  line  of  the  old 
one.^  By  this  process  of  partial  destruction  and  renewal  the  spit  retreats, 
keeping  pace  with  the  retreating  clilf.  At  an  earlier  stage  of  the  process 
the  spit  may  have  had  the  position  and  form  indicated  by  the  dotted  out- 
line, but  whatever  hooks  ft-iuged  its  inner  margin  have  disappeared  in  the 
process  of  retreat. 

'The  marsh  occnpying  part  of  the  space  between  the  spit  and  the  inaiuland  (Fig.  It)  is  only 
incidentally  connected  with  the  feature  under  discussion.  A  small  stream,  the  Don,  reaches  the  shore 
of  the  lake  within  the  tract  protected  from  waves  by  the  hook  and  is  thus  enabled  to  construct  a  delta 
with  its  sediment. 

-Report  on  the  preservation  and  improvement  of  Toronto  Harbor.  In  Supplement  to  Canadian 
Journal,  1854. 

'At  the  present  time  the  spit  is  divided  near  the  niiudle,  a  natural  breach  having  been  artificially 
prevented  from  healing.     The  portion  of  the  peninsula  fringed  by  successive  hooks  stands  as  au  island. 


LOOPED  BARS.  55 

The  landward  shifting  illustrated  by  the  Toronto  hook  affects  many 
embaidvments,  but-  not  all.  It  ordinarily  occurs  when  the  embankment  is 
built  in  deep  water  and  the  source  of  its  material  is  close  at  hand.  Wherever 
it  is  known  that  an  embankment  has  at  some  time  been  breached  by  the 
waves,  it  may  be  assumed  with  confidence  that  retreat  is  in  progress. 

As  retreat  progresses  the  layers  constituting-  the  embankment  are  trun- 
cated at  top,  and  new  layers  are  added  on  the  landward  side.  In  the  result- 
ing structure  the  prevailing  di})  is  landward  (Fig.  12),  and  it  is  thereby 
distinguished  from  all  other  forms  of  lacustrine  deposition.  This  structure 
was  first  described  and  explained  by  Fleming,  who  observed  it  in  a  railway 
cutting  through  an  ancient  spit.^ 

The  Loop.- Just  as  the  spit,  by  advancing  until  it  rejoins  the  shore,  becomes 
a,  bar,  so  the  completed  hook  may  with  propriety  be  called  a  looj)  or  a  looped 
bar.  There  is,  however,  a  somewhat  different  feature  to  which  the  name  is 
more  strikingly  applicable.  A  small  island  standing  near  the  main-land  is 
usually  furnished  on  each  side  with  a  spit  streaming  toward  the  land.  These 
spits  are  composed  of  detritus  eroded  from  the  lakeward  face  of  the  island, 
against  which  beat  the  waves  generated  through  the  l)road  expanse.  The 
currents  accompanj-ing  the  waves  are  not  unifoi-m  in  direction,  but  vary 
witli  the  wind  tlu'ough  a  wide  angle;  and  the  spits,  in  sympathy  with  the 
varying  direction  of  currents,  are  curved  inward  toward  the  island.  If  their 
extremities  coalesce,  they  constitute  together  a  perfect  loop,  resembling, 
when  mapped,  a  festoon  pendent  from  the  sides  of  the  island. 

Such  a  loop  in  the  fossil  condition,  that  is,  when  preserved  as  a  vestige 
of  the  shore  of  an  extinct  lake,  has  the  form  of  a  crater  rim,  the  basin  of 
the  original  lagoon  remaining  as  an  undfained  hollow.  The  accompanying 
illustration  (PI.  VI)  represents  an  island  of  Lake  Bonneville  standing  on  the 
-desert  near  what  is  known  as  the  "Old  River  Bed."  The  nucleus  of  solid 
rock  was  in  this  instance  nearly  demolished  before  the  work  of  the  waves 
was  arrested  by  the  lowering  of  the  water. 

The  Wave-built  Terrace.-It  has  already  bccu  pointed  out  that  when  a  separa- 
tion of  the  littoral  current  from  the  coast  line  is  lirought  about  bv  a  diverg- 
ence of  the  current  rather  than  of  the  coast  line,  there  are  two  cases,  in  the 

'Notes  on  the  Daveuport  gravel  diift.     Canaili.ui  Joarnal,  New  Series,  vol.  6,  1861,  pp.  247-253. 


56 


LAKE  BONNEVILLE. 


first  of  which  the  current  continues  at  the  surface,  while  in  the  second  it 
dives  beneath  the  surface.  It  is  now  necessary  to  make  a  further  distinc- 
tion. The  cun-ent  departing  from  the  sliore,  but  remaining  at  tlie  surface, 
may  continue  with  its  original  velocity  or  it  may  assume  a  greater  cross- 
section  and  a  diminished  velocity.  In  the  first  case  the  shore  drift  is  built 
into  a  spit  or  other  linear  embankment.  In  the  second  case  it  is  built  into 
a  terrace.  The  quantity  of  shore  diift  moved  depends  on  the  magnitude  of 
the  waves;  but  the  speed  of  transit  depends  on  the  velocity  of  the  current, 
and  wherever  that  velocity  diminishes,  the  accession  of  shore  di-ift  must 
exceed  the  transmission,  causing  accumulation  to  take  place.  This  accumu- 
lation occurs,  not  at  the  end  of  the  beach,  but  on  its  face,  carrpng  its  entire 
profile  lakeward  and  producing  by  the  expansion  of  its  crest  a  tract  of  new- 
made  land.  If  afterward  the  water  disappears,  as  in  the  case  of  an  extinct 
lake,  the  new-made  land  has  the  character  of  a  terrace.  A  cun-ent  which 
leaves  the  shore  by  descending,  practically  produces  at  the  shore  a  diminu- 
tion of  flow,  and  the  resulting  embankment  is  nearly  identical  with  that  of 
a  slackening  superficial  current. 

The  wave-built  terrace  is  distinct  from  the  wave-cut  terrace  in  that  it 
is  a  work  of  construction,  being  composed  entirely  of  shore  drift,  while  the 
wave-cut  terrace  is  the  result  of  excavation,  and  consists  of  the  pre-existent 
terrane  of  the  locality.  The  wave-built  terrace  is  an  advancing  embank- 
ment, and  its  internal  structure  is  characterized  by  a  lakeward  dip  (Fig.  13). 
It  is  thus  contrasted  with  the  retreating  embaidiment  (Fig.  12). 


Fig.  12.— Section  of  a  Linear  Embaukmcnt  retreating  landward.    Tliedolti-d  line  .sliiiws  llie  oiiyiu^il  posili(in  of  tbe  crest 


i^^^^^i^^iiiiil^^^sl^Mlii^MSsJMi^^Si^^;. 


Fig.  13.— Section  of  a  Wave-built  Terrace. 

The  surface  of  the  wave-built  terrace,  considered  as  a  whole,  is  level, 
but  in  detail  it  is  uneven,  consisting  of  parallel  ridges,  usually  curved.    Each 


WAVE-BUILT  TERRACES.  57 

of  these  is  referable  to  some  exceptional  siorm,  the  waves  of  which  threw 
the  shore  ch-ift  to  an  unusual  height. 

Wliere  the  shore  drift  consists  wholly  or  in  large  part  of  sand,  and  the 
prevailing  winds  are  toward  the  shore,  the  wave-built  terrace  gives  origin  to 
dunes,  which  are  apt  to  mask  its  normal  ribbed  structure. 

The  locality  most  favorable  for  the  formation  of  a  wave-built  terrace 
is  the  head  of  a  triangular  bay,  up  which  the  waves  from  a  large  body  of 
water  are  rolled  without  obstruction.  The  wind  sweeping  up  such  a  bay 
carries  the  surface  of  the  water  before  it,  and  the  only  return  current  is  an 
undertow  originating  near  the  head  of  the  bay.  The  superficial  advance  of 
the  water  constitutes  on  each  shore  a  littoral  current  conveying  shore  drift 
toward  the  head  of  the  bay,  and  as  these  littoral  currents  are  diminished 
and  finally  entirely  dissipated  by  absorption  in  the  undertow,  the  shore  di'ift 
taken  up  along  the  sides  of  the  bay  is  deposited.  If  the  head  of  the  bay  is 
acute,  the  first  embankment  built  is  a  curved  bar  tangent  to  the  sides  and  con- 
cave toward  the  open  water.  To  the  face  of  this  successive  additions  are 
made,  and  a  terrace  is  gradually  produced,  the  component  ridges  of  which 
are  approximately  parallel.  The  sharpest  curvature  is  usually  at  the  ex- 
treme head  of  the  bay. 

The  converging  currents  of  such  a  bay  give  rise  to  an  undertow  which 
is  of  exceptional  velocity,  so  that  it  transports  with  it  not  only  the  finest 
detritus  but  also  coarser  mattei',  such  as  elsewhere  is  usvially  retained  in  the 
zone  of  wave  action.  In  effect  there  is  a  resorting  of  the  material.  The 
shore  drift  that  has  traveled  along  the  sides  of  the  bay  toward  its  head,  is 
divided  into  two  portions,  the  finer  of  which  passes  out  with  the  reinforced 
undertow,  while  the  coarser  only  is  built  into  the  terrace. 

The  v-Terrace  and  v-Bar.-It  rcmalus  to  dcscribc  a  type  of  terrace  for  which  no 
satisfactory  explanation  has  been  reached.  The  shores  of  the  ancient  Pleis- 
tocene lakes  afford  numerous  examples,  Ijut  those  of  recent  lakes  are  nearly 
devoid  of  them,  and  the  writer  has  never  had  opportunity  to  examine  one 
in  process  of  formation.  They  are  triangular  in  ground  plan,  and  would 
claim  the  title  of  delta  were  it  not  appropriated,  for  they  simulate  the  Greek 
letter  more  strikingly  than  do  the  river-mouth  structures.  They  are  built 
against  coasts  of  even  outline,  and  usually,  but  not  always,  upon  slight 


58  LAKE  BONNEVILLE. 

salients,  and  they  occur  most  freqiientl}'  in  the  long,  narrow  arms  of  old 
lakes.  \ 

One  side  of  the  triangle  rests  against  the  land  and  the  opposite  angle 
points  toward  the  open  water.  The  free  sides  meet  the  land  with  short 
curves  of  adjustment,  and  appear  otherwise  to  he  normally  straight,  although 
they  exhibit  convex,  concave,  and  sigmoid  flexures.  The  growth  is  by  ad- 
ditions to  one  or  both  of  the  free  sides;  and  the  nucleus  appears  always  to 
have  been  a  miniature  triangular  terrace,  closely  resembling  the  final  struct- 
ure in  shape.  In  the  Bonneville  examples  the  lake  ward  slope  of  the  teiTace 
is  usually  very  steej)  down  to  the  line  where  it  joins  the  preexistent  slope 
of  the  bottom. 

There  seems  no  reason  to  doubt  that  these  embankments,  like  the 
others,  were  built  by  currents  and  waves,  and  such  being  the  case  the  for- 
mative currents  must  have  divercced  from  the  shore  at  one  or  both  the  land- 
ward  angles  of  the  terrace,  but  the  condition  detennining  this  divergence 
does  not  appear. 

In  some  cases  the  two  margins  appear  to  have  been  deteimined  by  cur- 
rents ajiproaching  the  terrace  (doubtless  at  different  times)  from  oj^posite 
directions;  and  then  the  terrace  margins  are  concave  outward,  and  their 
confluence  is  prolonged  in  a  more  or  less  irregular  point.  In  most  cases, 
however,  the  shore  drift  appears  to  have  been  carried  by  one  cm'rent  from 
the  mainland  along  one  margin  of  the  teiTace  to  the  apex,  and  by  another 
current  along-  the  remaining  side  of  the  terrace  back  to  the  mainland.  The 
contours  are  then  either  straight  or  convex. 

In  Lake  Bonnevnlle  it  happened  that  after  the  best  defined  of  these  ter- 
races had  attained  nearly  their  final  width  the  lake  increased  in  size,  so  that- 
they  Avere  immersed  beneath  a  few  feet  f)f  water.  Wliile  the  lake  stood  at 
the  higher  level,  additions  were  made  to  the  terraces  by  the  building  of  lin- 
ear embankments  at  their  outer  margins.  These  were  carried  to  the  water 
surface,  and  a  triangular  lagoon  was  imprisoned  at  eacli  l(>ialit\-.  The  sites 
of  these  lagoons  are  now  represented  by  flat  triangular  basins,  i-ach  walled 
in  by  a  bar  bent  in  the  fonn  of  a  V.  These  Ijars  were  at  first  observed 
without  a  clear  conception  of  the  terrace  on  which  they  were  founded,  and 
the  name  W-bar  was  applied.     The  V-bar,  while  a  conspicuous  feature  of 


a  S. GEOLOGICAL   SUPVEY 


LAKE  BONNEVILLE      PLVH 


I'LATS  Ol'   LOOl'Kl)    AM)   V-SllArKT)  KM15AN  K'MKNTS, 

OBSERVED    ON 
TBK  SHORES  OF  LAKE  I{0.\NEVlEEi:. 

o  I  8  3  ■tOOO_         _ 

SCALt:  t 


arrows  sfitiw 
on  171  w/t/r/f 
x  liri/'f/d 


1,  Siill   Mnixli  ,     .■>■„, lit'     I'.illii 

•-',   II.       A'„.v/    B.i.-.;    ,ir  IJra\,r   Crrrl.     Uaii,/, 
h'<.s;-ni'ir   lUillr  ,01,1   Hivrr  Ui-il . 

1..  SlIiWIllKW 

■'>.  Fri'tt    o/'  the    Mouriliiui 


6.  Haxl    Biixf  ,  Drrp   I'r  JtU: 

7 ,  U  sill,-  nl    did  Hirer  Bed 
\\,S\X\  U'f.y/    NtiAf  o/'  Fn.-irn  Mnnritfiin,. 
10,12      Prmxs    I'liUev.  rinir    Wa-iia     .s/nuu/ 
\'i ,          .Vf rt  r   StttrkLcn 


.luliu.t  Klcn  \  L'o.liUi 


DiMwn  t>v  C;  Tlioiul<sou 


TRIANGULAR  TERRACES.  59 

the  Bonne'salle  shores,  is  not  believed  to  be  a  normal  feature  of  lakes  main- 
taining a  constant  level. 

DRIFTING   SAND;    DUNES. 

The  dune  is  not  an  essential  shore  feature,  but  is  an  accessory  of  fre- 
quent occurrence. 

Dunes  are  formed  wherever  the  wind  drifts  sand  across  the  land.  The 
conditions  essential  to  their  production  are  wind,  a  supply  of  sand,  and 
sterility  or  the  absence  of  a  protective  vegetal  growth.  In  arid  regions 
sterility  is  afforded  by  the  climatic  conditions,  and  the  sand  furnished  by 
river  bars  laid  bare  at  low  water,  and  by  the  disintegration  of  sand  rocks, 
is  taken  up  1)y  the  wind  and  built  into  dunes;  but  where  rain  is  abundant, 
accumulations  of  such  sort  are  protected  by  vegetation,  and  the  only  sources 
of  sujjply  are  shores,  either  modern  or  ancient. 

Shore  drift  nearly  always  contains  some  sand,  and  is  frequently  com- 
posed exclusively  thereof  The  undertow  carries  off  the  clay,  which  might 
otherwise  hold  the  sand  particles  together  and  prevent  their  removal  by  the 
wind;  and  pebbles  and  bowlders,  which,  by  their  superior  weight  oppose 
wind  action,  are  less  able  to  withstand  the  attrition  of  littoral  transj)ortation, 
and  disappear  by  disintegration  from  any  train  of  shore  drift  which  travels 
a  considerable  distance.  Embankments  are  therefore  apt  to  be  composed 
largely  of  sand;  and  the  crests  of  embankments,  being  exposed  to  the  air 
during  the  intervals  between  great  storms,  yield  dry  sand  to  the  gentler 
winds. 

The  sand  drifted  from  the  crests  of  free  embankments,  such  as  barriers, 
spits,  and  bars,  quickly  reaches  the  water  on  one  side  or  the  other.  What 
is  blown  to  the  lakeward  side  falls  within  the  zone  of  wave  action,  and  is 
again  worked  Over  as  shore  drift.  What  is  blown  to  the  landward  side  ex- 
tends the  area  of  the  embankment,  correspondingly  encroaching  on  the 
lagoon  or  bay. 

Sand  blown  from  the  crests  of  embankments  resting  against  the  land, 
such  as  beaches  and  terraces,  will  spread  over  the  land  if  the  prevailing 
wind  is  favorabje.  In  cases  where  the  prevailing  Avind  is  toward  the  lake 
the  general  movement  of  sand  is,  of  course,  in  that  direction,  and  it  is  merely 


60  LAKE  BONNEVILLE. 

returned  to  the  zone  of  the  waves  and  readded  to  the  shore  drift;  but  where 
the  prevailing  winds  are  toward  the  land,  dunes  are  foiTned  and  slowly  rolled 
forward  by  the  wind.  The  supply  of  diy  sand  afforded  by  beaches  is  com- 
paratively small,  and  dunes  of  magnitude  are  not  often  formed  from  it.  The 
great  sand  magazines  are  wave-built  terraces,  and  it  is  from  these  that  the 
trains  of  sand  so  formidable  to  agriculture  have  originated. 

The  sands  accumulated  on  the  shores  of  lakes  and  oceans  now  extinct 
are  sometimes  so  clean  that  vegetation  acquires  no  foothold,  and  the  wind 
still  holds  dominion.  The  "oak  openings"  of  Western  States  are  usually 
of  this  nature;  and  in  the  Great  Basin  there  are  numerous  trains  of  dunes 
conveying  merely  the  sand  accumulated  on  the  shores  of  the  Pleistocene 
lakes. 

One  product  of  littoral  deposition — the  delta — remains  undescribed; 
but  this  is  so  distinct  from  the  embankment,  not  only  in  form  but  in  process 
of  construction,  that  its  consideration  will  be  deferred  until  the  interrelations 
of  the  three  processes  already  described  have  been  discussed. 

THE  DISTRIBUTIOlSr  OF  WAVE-WROUGHT  SHORE  FEATURES. 

Upon  every  coast  there  are  certain  tracts  undergoing  erosion;  certain 
others  receive  the  products  of  erosion,  and  the  intervals  are  occupied  by  the 
structures  peculiar  to  transportation.  Let  us  now  inquire  what  are  the  con- 
ditions determining  these  three  phases  of  shore  shaping. 

It  will  be  convenient  to  consider  first  the  conditions  of  transportation. 
In  oi'der  that  a  particular  portion  of  shore  shall  be  the  scene  of  littoral  trans- 
portation, it  is  essential,  first,  that  there  be  a  supply  of  shore  di-ift;  second, 
that  there  be  shore  action  by  waves  and  currents;  and  in  order  that  the 
local  process  be  transportation  simply,  and  involve  neither  erosion  nor  depo- 
sition, a  certain  equilibrium  must  exist  between  the  quantity  of  the  shore 
drift  on  the  one  hand  and  the  power  of  the  waves  and  cui-ri'uts  on  the  other. 
On  the  whole  this  equilibrium  is  a  delicate  one,  but  within  certain  narrow 
limits  it  is  stable.  That  is  to  say,  there  are  certain  slight  varisUions  of  the 
individual  conditions  of  equilibrium,  which  distm-b  the  equilibrium  only  in 
a  manner  tending  to  its  immediate  readjustment.     For  example,  if  the  shore 


DISTKIBUTIOJ!^  OF  EUOSION  AND  DEPOSITION.  61 

drift  receives  locally  a  small  increment  from  stream  drift,  this  increment,  by 
adding  to  the  shore  contour,  encroaches  on  the  margin  of  the  littoral  ciuTcnt 
and  produces  a  local  acceleration,  which  acceleration  leads  to  the  removal 
of  the  obstruction.  Similarly,  if  from  some  temporary  cause  there  is  a  local 
defect  of  shore  drift,  the  resulting  indentation  of  the  shore  contour  slackens 
the  littoral  current  and  causes  deposition,  whereby  the  equilibrium  is  restored. 
Or  if  the  force  of  the  waves  is  broken  at  some  point  by  a  temporary  obstruc- 
tion outside  the  line  of  breakers,  as  for  example  by  a  wreck,  the  local  dimi- 
nution of  wave  agitation  produces  an  accumulation  of  shore  drift  whereby 
the  littoral  cxirreut  is  narrowed  and  thus  accelerated  until  an  adjustment  is 
reached. 

Outside  the  limits  thus  indicated  everything  which  disturbs  the  adjust- 
ment between  quantity  of  shore  drift  and  capacity  of  shore  agents  leads  either 
to  progressive  local  erosion  or  else  to  progressive  local  deposition.  The 
stretches  of  coast  which  either  lose  or  gain  ground  are  decidedly  in  excess  of 
those  which  merely  hold  their  own. 

An  excessive  stipply  of  shore  ch'ift  over  and  above  what  the  associated 
curi'ent  and  Avaves  are  competent  to  transport  leads  to  deposition.  This 
occurs  where  a  stream  of  some  magnitude  adds  its  quota  of  debris.  A  mod- 
erate excess  of  this  nature  is  disposed  of  by  the  formation  of  a  wave-built 
terrace  on  the  lee  side  of  the  mouth  of  the  stream,  that  is,  on  the  side  toward 
which  flows  the  littoral  current  accompanying  the  greatest  weaves.  A  great 
excess  leads  to  the  formation  of  a  delta,  in  which  the  stream  itself  is  the  con- 
structing agent  and  the  influence  of  waves  is  subordinate. 

On  the  other  hand,  there  is  a  constant  loss  of  shore  drift  by  attrition, 
the  particles  in  transit  being  gradually  reduced  in  size  until  they  are  removed 
from  the  littoral  zone  by  the  undertow.  As  a  result  of  the  defect  thus  occa- 
sioned, a  part  of  the  energy  of  the  waves  is  expended  on  the  subjacent 
terrane,  and  the  work  of  transportation  is  locally  accompanied  by  a  sufficient 
amount  of  erosion  to  replenish  the  wasting  shore  drift.  For  tlie  maintenance 
of  a  continuous  beach  in  a  permanent  position,  it  appears  to  be  necessary 
that  small  streams  shall  contribute  enough  debris  to  compensate  for  the 
waste  by  attrition. 


62  LAKE  BONNEVILLK. 

Theoretically,  transportation  must  be  exchanged  for  erosion  wherever 
there  is  a  local  increase  iu  the  magnitude  of  waves,  and  for  deposition  where 
there  is  a  local  decrease  of  waves ;  but  practically  the  proportions  of  waves 
are  so  closely  associated  with  the  velocities  of  the  accompanying  cuiTents 
that  their  effects  have  not  been  distinguished. 

The  factor  which  most  frequently,  by  its  variation,  disturbs  the  equi- 
librium of  shore  action  is  the  littoral  current.  It  has  already  been  pointed 
out  that  wherever  it  leaves  the  shore,  shore  di-ift  is  deposited;  and  it  is 
equally  true  that  wherever  it  comes  into  existence  by  the  impinging  of  an 
open-water  current  on  the  shore,  shore  diift  is  taken  up  and  the  terrane  is 
eroded.  It  has  been  shown  also  that  the  retardation  of  the  littoral  cm-rent 
produces  deposition,  and  it  is  equally  true  that  its  acceleration  causes  ero- 
sion. Every  variation,  therefore,  in  the  direction  or  velocity  of  the  cmrent 
at  the  shore  has  a  definite  effect  in  the  determination  of  the  local  shore 
process. 

Reentrant  angles  of  the  coast  are  always,  and  reentrant  cm'ves  are 
usually,  places  of  deposition.  The  reason  for  this  is  twofold:  first,  currents 
which  follow  the  shore  move  with  diminished  velocity  in  passing  reentrants; 
second,  cun-ents  directed  toward  the  shore  escape  from  reentrants  only  by 
undertow,  and,  as  heretofore  explained,  build  terraces  at  the  heads  of  the 
embayments. 

Salient  angles  are  usually  eroded,  and  salient  curves  nearly  always, 
the  reasons  being,  first,  that  a  current  following  the  shore  is  relatively  swift 
opposite  a  salient,  and,  second,  that  a  current  directed  toward  the  shore  is 
apt  to  be  divided  by  a  salient,  its  halves  being  converted  into  littoral  cur- 
rents transporting  shore  drift  in  opposite  directions  aivaij  from  the  salient. 

Some  salient  angles,  on  the  contrary,  grow  by  deposition.  Tliis  occurs 
where  the  most  important  current  approaches  by  following  the  shore  and  is 
thi-own  off  to  deep  water  by  a  salient.  The  most  notable  instances  ai-c  found 
on  the  sides  of  narrow  lakes  or  arms  of  lakes,  iu  which  case  currents  approach- 
ing from  the  direction  of  the  length  are  accompanied  by  greater  waves  than 
those  blown  from  the  direction  of  the  opposite  shore,  and  therefore  dominate 
in  the  detei-mination  of  the  local  action. 


SIMPLIFICATION  OF  COAST  LINES.  63 

It  thus  appears  that  there  is  a  general  tendency  to  the  erosion  of  salients 
and  the  filling  of  embayments,  or  to  tlie  simplification  of  coast  outlines.  This 
tendency  is  illustrated  not  only  by  the  shores  of  all  lakes,  but  by  the  coasts  of 
all  oceans.  In  the  latter  case  it  is  slightly  diminished  by  the  action  of  tides, 
which  occasion  currents  tending  to  keep  open  the  mouths  of  estuaries,  but 
it  is  nevertheless  the  prevailing  tendency.  The  idea  which  sometimes  ap- 
pears in  popular  writings  that  embayments  of  the  coast  are  eaten  oiit  by 
the  ocean  is  a  survival  of  the  antiquated  theory  that  the  sculpture  of  the 
land  is  a  result  of  "marine  denudation."  It  is  now  understood  that  the  diver- 
sifies of  land  topography  are  wrought  by  stream  erosion. 

Figure  8,  representing  about  seven  miles  of  the  shore  of  Lake  Ontario, 
illustrates  the  tendency  toward  simplification.  Each  bluff  of  the  shore  marks 
the  truncation  by  the  waves  of  a  cape  that  was  originally  more  salient.  Each 
beach  records  the  partial  filling  of  an  original  bay.  Each  bar  is  a  wave- 
built  structure  partitioning  a  deep  reentrant  from  the  open  lake.  The  la- 
goons receive  the  detritus  from  the  streams  of  the  land  and  are  filling;  partly 
for  this  reason  there  is  a  local  defect  of  shore  drift,  and  tlie  coast  is  receding 
by  erosion;  and  by  this  double  process  the  original  reentrants  are  suffering 
complete  effacement.  For  the  original  coast  line — a  sinuous  contour  on  a 
surface  modeled  by  glacial  and  fluvial  agencies — will  be  substituted  a  rela- 
tively short  line  of  simple  curvature. 

The  simplification  of  a  coast  line  is  a  work  involving  time,  and  the 
amount  of  work  accomplished  on  a  particular  coast  aflbrds  a  relative  meas- 
ure of  the  time  consumed.  There  are  many  modif}'ing  conditions — the 
fetch  of  waves,  the  off-shore  depth,  the  material  of  the  land,  the  original 
configuration,  etc. — and  these  leave  no  hope  of  an  absolute  measure;  but 
it  is  possible  to  distinguish  the  young  coast  from  the  mature.  When  a 
water  level  is  newly  established  against  land  with  sinuous  contour,  the  first 
work  of  the  waves  is  the  production  of  the  beach  profile.  On  the  gentlest 
slopes  they  do  this  by  excavating  the  terrane  at  the  point  where  they  first 
break  and  throwing  the  material  shoreward  so  as  to  build  a  barrier.  On  all 
other  slopes  they  establish  the  profile  by  carving  a  terrace  with  its  correla- 
tive clifi".     The  coarser  products  of  terrace-cutting  gather  at  the  outer  edge 


64  LAKE  BONNEVILLE. 

of  the  terrace,  helping  to  increase  its  breadth ;  the  finer  fall  in  deeper  water 
and  help  to  equalize  the  off-shore  depth.  Tlie  terrace  gradually  increases 
by  the  double  process  of  cutting  and  iiUing  until  it  has  attained  a  certain 
minimum  width  essential  to  the  transportation  of  shore  (L-ift.  This  A\idth  is 
for  each  locality  a  function  of  the.  size  of  the  greatest  waves.  Before  it  is 
reached,  the  fragments  detached  from  the  cliff  linger  but  a  short  time  on  the 
face  of  the  ten-ace;  after  a  few  excursions  uj)  and  down  the  slope  they  come 
to  rest  at  the  edge  of  the  deeper  water.  When  it  is  reached — wlien  the 
beach  profile  is  complete — the  excavated  fragments  torn  from  the  cliff  no 
longer  escape  from  the  zone  of  wave  action,  but  are  rolled  to  and  fro  l)y  the 
waves  of  every  storm,  lose  their  angles  by  attrition,  and  are  drifted  along 
by  the  shore  cun-ent.  It  may  happen  that  the  material  of  the  cliff  is  a 
gravel,  already  rounded  by  some  earlier  and  independent  process,  but  Avhen 
this  is  not  tlie  case,  the  cut-terraces  of  adolescent  and  mature  coasts  are 
distinguished  by  the  angular  fomis  on  the  one  hand  and  the  rounded  forms 
on  the  other  of  the  associated  detritus.  When  the  formation  of  shore  drift 
has  once  been  begun,  its  further  development  and  the  development  of  effi- 
cient shore  currents  are  gradual  and  by  reciprocation.  The  spanning  of 
minor  recesses  of  the  coast-line  by  its  beach  helps  to  smooth  the  way  for 
the  shore  current,  and  the  current  promotes  the  beach.  Embankments  come 
later,  when  ways  have  been  straightened  for  the  current  and  shore  drift, 
and  those  first  constructed  usually  attempt  the  partition  of  only  small  em- 
bayments.  The  more  extended  and  powerful  shore  currents,  competent  to 
span  the  bays  between  the  greater  headlands,  become  possible  only  after 
minor  rugosities  of  coast  and  bottom  have  disappeared. 

LoAV  but  nearly  continuous  sea-cliffs  mark  the  adolescent  coast;  simple 
contours  and  a  cordon  of  sand,  interspersed  with  high  cliff's,  mark  the  matui*e 
coast.  As  a  result  of  the  inconstancy  of  the  relations  of  land  and  water,  it 
is  probable  that  all  coasts  fall  under  these  heads,  but  Richthofen  lias  sketched 
the  features  of  the  theoretic  senile  coast.^  As  sea-cliffs  retreat  and  terraces 
grow  broader  the  energy  of  the  waves  is  distributed  over  a  wider  zone  and 
its  erosive  work  is  diminished.     The  resulting  defect  of  shore  drift  permits 

'  Fuhrer  fur  Forscbungsreisende,  p.  338. 


ADOLESCENT,  MATURE  AND  SENILE  COASTS.  65 

the  erosion  of  embankments,  and  tlie  withdrawal  of  their  protection  extends 
the  line  of  cliff;  but  eventually  the  whole  line  is  driven  Ijack  to  its  limit 
and  erosion  ceases.  The  cliffs,  no  longer  sapped  by  the  waves,  yield  to 
atmospheric  agencies  and  blend  with  the  general  topography  of  the  land. 
Shore  drift  is  still  supplied  by  the  streams  and  is  spread  over  the  broad  lit- 
toral shoal,  ^\■here  it  lies  until  so  comminuted  by  the  waves  that  it  can  float 
away. 

The  length  of  the  period  of  adolescence  varies  with  local  conditions. 
Where  the  waves  are  powerful,  maturity  comes  sooner  than  where  they  are 
weak.  It  comes  sooner,  too,  where  the  material  to  be  moved  by  the  waves 
is  soft  or  incoherent  than  where  it  is  hard  and  tirm;  and  it  comes  early 
where  the  submerged  contours  and  the  contour  at  the  water's  edge  have 
few  irregularities.  Different  parts  of  the  same  coast  accordingly  illustrate 
different  stages  of  development.  The  shores  of  Lake  Bonneville  are  in 
general  matui'e,  but  in  small  sheltered  bays  they  are  adolescent.  The 
shore  of  Lake  Ontario  is  in  general  mature,  being  traced  on  a  surface  of 
glacial  drift,  but  near  the  outlet  is  a  region  of  bare,  hard  rock  disposed  in 
promontories  and  islands,  and  there  much  of  the  coast  is  adolescent. 

The  classic  "parallel  roads"  of  Glen  Roy  in  Scotland  illustrate  the  ado- 
lescent type,  and  this  although  the  local  conditions  favor  rapid  development. 
The  smooth  contoiu's  of  the  valley  gave  no  obstruction  to  shore  currents, 
depth  and  length  of  lake  permitted  the  raising  of  large  waves,  and  a  mantle 
of  glacial  drift  afforded  material  for  shore  drift;  but  the  beach  profile  was 
not  completed,  the  bowlders  of  the  narrow  terraces  are  still  subangular, 
and  there  are  no  eml)ankments.  It  is  fairly  inferred  that  the  time  repre- 
sented by  each  shore-line  was  short. 

STREAM  WORK;  THE  DELTA. 

The  detritus  brought  to  lakes  by  small  streams  is  overwhelmed  by  shore 
drift  and  merges  with  it.  The  tribute  of  large  streams,  on  the  contrary, 
overwhelms  the  shore  drift  and  accumulates  in  deltas.  In  the  formation  of 
a  normal  delta  the  stream  is  the  active  agent,  the  lake  is  the  passive  recipient, 
and  waves  play  no  essential  part. 

MON  I 5 


66  LAKE  liONNEVILLE. 

Tlie  process  of  delta  formation  depends  almost  wholly  on  the  following 
law:  The  ((qxidtij  and  compdence  of  a  stream  for  the  transporlatiou  of  detritus 
are  increased  and  diminished  hij  the  increase  and  diminution  of  the  velocity.  1  lie 
capacity  of  a  stream  is  measured  by  the  total  load  of  deljris  of  a  given  fine- 
ness which  it  can  cany.  Its  competence  is  measured  by  the  maximiun  size 
of  tlie  jiartioles  it  can  move.  A  swift  current  is  able  to  transport  both  more 
matter  and  coarser  matter  than  a  slow  current.  The  competence  depends 
on  tlie  velocity  of  the  water  at  the  bottom  of  the  chamiel,  for  tlie  Lu-gest 
particles  the  stream  can  move  are  merely  rolled  along  tlie  bottom.  Finer 
particles  are  lifted  from  the  bottom  by  threads  of  current  tending  more  <ir 
less  upward,  and  l)efore  they  sink  again  are  carried  forward  by  the  general 
tlow.  Their  suspension  is  initiated  by  the  bottom  current,  but  the  length 
and  speed  of  their  excursi(m  depend  on  the  general  velocity  of  the  current. 
Capacity  is  therefore  a  function  of  the  velocity  of  the  more  superticial  threads 
of  current  as  well  as  of  those  which  follow  the  bottom. 

Suppose  tliat  a  river  freighted  with  the  waste  of  the  Jand  is  newly  made 
tributary  to  a  lake.  Its  water  flows  to  the  shore,  and  shoots  out  thence 
o^'er'  the  relatively  still  lake  water  until  its  momentum  has  been  communi- 
cated by  friction  to  so  large  a  body  of  water  as  to  practically  dissipate  its 
velocity.  From  the  shore  outward  the  velocity  at  the  bottom  is  the  velocity 
of  the  lake  water  and  not  that  of  the  river  water,  and  is  inconsiderable.  The 
entire  load  conse(][uently  sinks  to  a  final  resting  place  and  becomes  a  deposit. 
The  coarse  particles  go  down  in  iimnediate  contiguity  to  the  shore.  Tlie 
finest  are  carried  far  out  before  they  escape  from  the  su})eiiicial  stratum  of 
river  water. 

The  sinking  of  thc!  coarse  material  at  the  shore  has  tlie  effect  of  1)uild- 
ing  out  a  platform  at  the  level  of  the  bottom  of  the  river  cluumel.  Po.stulate 
the  construction  of  this  ])latform  for  some  distance  from  the  sliore  without 
any  modification  of  the  longitudinal  profile  of  the  river,  the  river  surface 
descending  to  the  shore  and  then  becoming  horizontal.  Evidently,  the  hor- 
izontal })ortion  has  no  energy  of  descent  to  propel  it,  and  yet  is  opposed  by 
friction;  its  velocity  is,  therefore,  retarded,  its  capacity  and  competence  are 

I  It  m  said  tbat  some  glacier-feil  streams  ou  entering  lakes  pass  iiuJer  instead  of  over  the  lake 
water  and  tbac  i)eculiar  delta  features  result,  but  tbese  are  uot  fully  described. 


DELTA  BUILDING.  67 

consequently  diminished,  and  it  tb-ops  some  of  its  load,  llie  fall  of  detritus 
builds  u])  the  bottom  at  the  point  where  it  takes  place,  and  causes  a  check- 
ing of  the  current  immediately  above  (up  stream).  This  in  turn  causes  a 
depo;;it;  an<l  a  reciprocation  of  retardation  ;uid  deposition  continues  until 
the  profile  of  the  stream  has  acquired  a  continuous  grade  from  its  mf>uth  at 
the  extremity  nf  the  new  platform  backward  to  some  steeper  part  of  its 
channel — a  continuous  grade  sufficient  to  give  it  a  velocity  adequate  to  its 
load.  Tlie  postulate  is,  of  course,  ideal.  The  river  does  not  in  fact  build 
a  level  bed  and  afterward  change  it  to  a  slope,  but  carries  forward  the  whole 
work  at  once,  maintaining  continuously  an  adjustment  between  its  grade 
and  its  work.  Moreover,  since  the  deposition  begins  at  some  distance  from 
the  mouth,  the  lessening  load  does  not  require  a  uniform  grade  and  does 
not  produce  it.  The  grade  diminishes  gradually  lakeward  to  the  foot  of  the 
deposit  slope,  so  that  the  longitudinal  profile  is  slightly  concave  upward. 
At  the  head  of  the  deposit  slope  there  is  often  an  abrupt  change  of  grade. 
At  its  foot,  where  the  maximum  deposit  is  made,  there  is  an  abrupt  change 
of  a  double  character;  the  incline  of  the  river  surface  is  exchanged  for  the 
horizontal  plane  of  the  lake  surface;  the  incline  of  the  river  bottom  is  ex- 
changed for  the  steeper  incline  of  the  delta  front. 

The  river  current  is  swifter  in  the  middle  than  at  the  sides,  and  on  a 
deposit  slope,  where  velocity  is  nicely  adjusted  to  load,  the  slight  retarda- 
tion at  the  sides  leads  to  deposition  of  suspended  matter.  A  bank  is  thus 
produced  at  either  hand,  so  that  the  water  flows  down  an  elevated  sluice  of 
its  own  construction.  The  sides  are  built  up  pari  passu  with  the  bottom, 
but  inasmuch  as  they  can  be  increased  only  by  overflow,  they  never  quite 
reach  the  flood  level  of  the  water  surface.  A  river  thus  contained,  and  a 
river  channel  thus  constructed,  constitute  an  unstable  combination.  So  loner 
as  the  bank  approximates  closely  to  the  level  of  the  surface  at  flood  stage, 
the  current  across  the  bank  is  slovyer  than  the  current  of  the  stream,  and 
deposits  silt  instead  of  excavating;  but  whenever  an  accidental  cause  so 
far  lowers  the  bank  at  some  point  that  the  current  across  it  during  flood 
no  longer  makes  a  deposit,  there  begins  an  erosion  of  the  bank  which 
increases  rapidly  as  the  volume  of  escaping  water  is  augmented.  A 
side  channel  is  thus  produced,  which  eventually  becomes  deeper  than  the 


68  LAKE  BONNEVlLLli;. 

main  or  oriq'inal  cliannel  and  draws  in  the  greater  part  or  perlia]is  all  of  the 
water.  The  ability  of"  the  new  channel  to  drain  the  old  one  depends  on  two 
things:  first,  the  outer  slope  of  the  bank,  from  the  circumstances  of  its  con- 
struction, is  steeper  than  the  descent  of  the  bottom  of  the  channel;  second, 
the  first-made  channel,  although  originally  following  the  shortest  route  to 
the  lake,  has  so  far  increased  its  length  by  the  extension  of  its  mouth  that 
the  water  escaping  over  its  bank  may  find  a  shorter  route.  The  river 
channel  is  thus  shifted,  and  its  mouth  is  transferred  to  a  new  point  on  the 
lake  shore. 

Repetition  of  this  process  transfers  the  work  of  alluAnal  deposition  from 
place  to  place,  and  causes  the  river  to  build  a  sloping  plain  instead  of  a 
simple  dike.  The  lower  edge  of  the  plain  is  everywhere  equidistant  from 
the  head  of  the  deposit  slope,  and  has  therefore  the  fonu  of  a  circular  arc. 
The  inclination  is  in  all  directions  the  same,  varying  only  with  the  dimin- 
ishing grade  of  the  deposit  slope,  and  the  fomi  of  the  plain  is  thus  approxi- 
mately conic.  It  is,  in  fact,  identical  with  the  product  of  land-shaping  known 
as  the  alluvial  cone  or  alluvial  fan.  The  symmetry  of  the  ideal  form  is 
never  attained  in  fact,  because  the  process  of  shifting  implies  inequality  of 
surface,  but  the  approximation  is  close  in  cases  where  the  grade  of  the 
deposit  slope  is  high,  or  where  the  area  of  the  delta  is  large  as  compared 
with  the  size  of  the  channel. 


m 


''&^////«ilyX^^Mi, . 


Fin.  14.— Section  of  a  Delta. 


At  the  lake  shore  the  manner  of  deposition  is  ditVcrcnt.  The  heavier 
and  coarser  part  of  the  river's  detrital  load,  that  which  it  j)ushes  and  rolls 
along  the  bottom  instead  of  earring  by  suspension,  is  emptied  into  the  lake 
and  slides  down  the  face  of  the  delta  with  no  impulse  but  that  given  by  its 
own  weight.  The  slojje  of  the  delta  face  is  the  angle  of  repose  of  this  coarse 
material,  subject  to  such  modification  as  may  result  from  agitation  by  waves. 


DELTA  STRUCTURE.  69 

The  finer  part  of  the  detritus,  that  which  is  transported  by  sns]:)ension,  is 
carried  beyond  the  delta  face,  and  sinks  more  or  less  slowly  to  the  bottom. 
Its  disti'ibution  depends  on  its  relative  fineness,  the  extremely  fine  material 
being  widely  diffused,  and  the  coarser  falling  near  the  foot  of  the  delta  face. 
The  depth  of  the  deposit  formed  from  suspended  material  is  greatest  near 
the  delta  and  diminishes  gradually  outward,  so  that  tlie  sloj)e  of  the  delta 
face  merges  by  a  curve  with  the  slope  of  the  bottom  beyond. 

As  the  delta  is  built  lakeward,  the  steeply  inclined  layers  of  the  delta 
face  are  superjiosed  over  the  more  level  strata  of  the  lake  bottom,  and  in 
turn  come  to  support  the  gently  inclined  layers  of  the  delta  plain,  so  that 
any  vertical  section  of  a  normal  delta  exhibits  at  the  top  a  zone  of  coarse 
material,  bedded  with  a  gentle  lakeward  inclination,  then  a  7.one  of  similar 
coarse  material,  the  laminations  of  which  incline  at  a  high  angle,  and  at 
bottom  a  zone  of  fine  material,  the  laminations  of  Avhich  are  gently  inclined 
and  unite  by  curves  with  those  of  the  middle  zone. 

The  characters  of  the  fossil  delta,  or  the  delta  as  it  exists  after  the  des- 
iccation of  the  lake  concerned  in  its  formation,  are  as  follows:  The  upper 
surface  is  a  terrace  with  the  form  of  an  alluvial  fan.  The  lower  slo})e  or 
face  is  steep,  ranging  from  10°  to  25°;  it  joins  the  upper  slope  by  an  angle 
and  the  plain  below  by  a  curve.  The  line  separating  the  upper  surface  from 
the  outer  slope  or  face  is  horizontal,  and,  in  common  with  all  other  horizon- 
tal contours  of  the  structure,  is  approximately  a  circular  arc.  The  upper 
or  landward  limit  of  the  upper  surface  is  a  line  horizontally  uneven,  depend- 
ing on  the  contours  of  the  antecedent  topography.  The  lower  limit  of  the 
face  is  a  vertically  uneven  line,  depending  on  the  antecedent  topography  as 
modified  by  lake  sediments.  The  material  is  detrital  and  well  rounded;  it 
exhibits  well-marked  lines  of  deposition,  rarely  taking  the  character  of  bed- 
ding. The  structure  as  seen  in  section  is  tripartite  (Fig.  15).  In  the  upper 
division  the  lines  of  deposition  are  parallel  to  the  upper  surface  of  the  delta; 
in  the  middle  division  they  are  parallel  to  the  steep  outer  face,  and  in  the 
lower  division  they  are  gently  inclined.  The  separation  of  the  middle  divis- 
ion from  the  lower  is  obscure.  Its  separation  from  the  upper  is  definite  and 
constitutes  a  horizontal  plane.  The  fossil  delta  is  invariably  divided  into 
two  parts  by  a  channel  running  from  its  apex  to  some  part  of  its  periphery 


70 


LAKE  BONNEVILLE. 


and  occupied  l)y  a  stream,  the  agent  of  its  construction  Ijccoming,  under 
changed  conditions  of  base  level,  the  agent  of  demolition. 

The  ftm-like  outline  of  the  normal  delta  is  iiioditicd  wlierever  wave  :ic- 
tion  lias  an  importance  comparable  with  that  of  stream  fiction.  Among  tlie 
great  variety  of  fonns  resulting  from  the  combination  of  tlic  two  agencies, 

there  is  one  wliidi  repeats  itself  with  suf- 
ficient frequency  to  deserve  special  men- 
tion.    It  occin-s  where  the  force  of  the 

)unt 
tlie 
delta  is  inconsiderable.  In  such  case 
the  shore  current  from  either  direction 
is  deflected  by  the  mass  of  the  delta,  and 
wave  action  adjusts  the  contour  of  the 
delta  to  conformitv  with  the  deflected 
shore  current.  If  the  ANave  influences 
from  oj)posite  directions  are  equal,  the 
delta  takes  the  form  of  a  symmetric  tri- 
aiiffle  similar  to  that  of  tlu'  V-terrace. 

Numerous  illustrations  are  to  be  seen 
on  the  shores  of  Seneca  and  CaAiiga 
Lakes,  where  the  conditions  are  peculiarly  favorable.  The  lake  is  long 
and  narrow,  so  that  nil  the  efficient  wave  action  is  associated  with  strong 
shore  currents,  and  these  alternate  in  dii'ection.  The  predominant  rock  of 
the  sides  is  a  soft  slude,  so  easilv  triturated  l)v  tlie  waves  tliat  the  entire 
product  of  its  erosion  escapes  with  the  undertow,  and  no  shore  drift  remains. 
The  sides  are  straight,  and  each  tributary  stream  l)uilds  out  ii  little  proinon- 
torv  ;it  its  month,  to  wliicli  the  waves  ffive  form.  Some  of  these  triauii'ular 
deltas  (miiIxmIv  perfectlv  tlu'  Greek  letter,  Init  tliev  turn  tlu*  aj)ex  toward  tla* 
wati'i-  instead  of  towanl  tlw*  laud. 


Fig.  15. — Verlitul  section  in  :i  Delta,  .sliowiuj;  the  i\,p\ 
cal  siiccessiou  of  strata. 


THE  WALLING  IN  OF  "WALLED"  LAKES.  71 


ICE  WORK ;  THE  RAMPART. 

This  feature  does  not  belong  to  lakes  in  general,  but  is  of  locjil  and 
exceptional  occurrence.  It  was  named  the  "Lake  Rampart"  by  Hitchcock, 
who  gave  the  first  satisfactory  accoinit  of  its  origin.'  Earlier  observations, 
containing  the  germ  of  the  exjjlanation  of  the  phenomenon,  wci-e  made  by 
Lee^  and  Adams.'  A  later  and  indepen- 
dent explanation  was  given  by  White.* 

Tn  ignorance  of  ITitchcock's  description, 
I  yave  credit  in  the  Fifth  Amuial  Keijort  of 

^  '  Fig.  16.— Section  ol  a  r.nTiipni I. 

the  U.  S.  Geological  Survey  to  White,  and 

myself  proposed  the  name  "Shore  Wall."  I  now  substitute  Hitclicock's 
name,  "Rampart",  being  moved  thereto  not  only  by  the  priority  and  the 
eminent  fitness  of  the  name,  bnt  by  the  consideration  that  "Shore  Wall"  is 
liable  to  be  confounded  with  "Sea  Wall",  a  term  applied  on  some  marine 
coasts  to  steep-faced  endiankments  of  shingle. 

The  ice  on  the  surface  of  a  lake  expands  while  forming,  so  as  to  crowd 
its  edge  against  the  shore.  A  further  lowering  of  tem})erature  produces 
contraction,  and  this  ordinarily  results  in  the  opening  of  vertical  fissures. 
These  admit  the  water  from  below,  and  by  the  freezing  of  that  water  they 
are  filled,  so  that  when  expansion  follows  a  subsequent  rise  of  temperature 
the  ice  cannot  assume  its  original  position.  It  consequently  increases  its  t(  >t;d 
area  and  exerts  a  second  thrust  upon  the  shore.  Where  the  shorts  is  iil)rnpt, 
the  ice  itself  yields,  either  bv  crushing  at  the  margin  or  by  tlm  formation 
of  anticlinals  elsewhere;  but  if  the  shore  is  generally  shelving,  the  margin 
of  the  ice  is  forced  up  the  acclivity,  and  carries  with  it  any  1)owlders  or  other 
loose  material  about  which  it  may  have  frozen.  A  second  lowering  of  tem- 
perature does  not  withdraw  the  protruded  ice  margin,  but  initiates  other 
cracks  and  leads  to  a  repetition  of  the  shoreward  thrust.  The  process  is 
repeated  from  time  to  time  during  the  winter,  but  ceases  with  the  melting  of 


'Lake  Ramparts  in  Vermont.     By  Clias.  H.  Hitchcock.     In  Proe.  Am.  Ass.  Adv.  Sci.,  vol.  1.3, 
1860,  p.  335. 

^C.  A.  Lee.     Am.  Jour.  Sci.,  vol.  5,  1822,  pp.  34-37,  and  vol.  9,  1825,  pp.  2.39-241. 
'J.  Adams.     Am.  Jour.  Sci.,  vol.  9,  1825,  p)(.  13(>-144. 
*C.  A.  White.     Am.  Naturalist,  vol.  2,  IHi/.i,  pp.  14G-149. 


72  LAKE  BONNEVILLE. 

the  ice  in  the  spring.  The  ice  formed  the  ensuing  winter  extends  only  to 
the  water  margin,  and  hy  the  winter's  oscilhitions  of  temperature  can  be 
thrust  Landward  only  to  a  certain  distance,  determined  by  the  size  of  the 
lake  and  the  local  climate.  There  is  thus  for  each  locality  a  definite  limit, 
beyond  whicli  the  ])rojection  of  bowlders  cannot  l)e  earned,  so  tliat  all  are 
deposited  along  a  common  line,  where  they  constitute  a  wall  oi'  ramjinrt. 

The  base  of  a,  rampart  stands  somewhat  above  and  beyond  the  ordinary 
mai'gin  of  tlie  water.  It  is  parallel  to  the  water  margin,  following  its  inflec- 
tions. Its  size  is  ])robably  determined  in  fact  by  the  supply  of  matenal,  but 
there  must  also  be  a  limit  dependent  on  the  strength  of  the  ice  formed  in  the 
given  locality.  Its  material  is  usually  coarse,  containing  bowlders  such  as 
the  waves  generated  on  the  same  lake  would  be  unable  to  move.  These 
iw.vy  be  either  smooth  or  angular,  heavy  or  light,  the  process  of  accunuda- 
tion  involvino-  no  discrimination. 

Ramparts  are  not  found  on  the  margins  of  large  lakes,  for  whatever 
record  the  ice  of  winter  may  make  is  obliterated  by  the  storm  waves  of  sum- 
mer. Neither  do  they  occur  on  the  shores  of  very  deep  lakes,  for  such  do 
not  admit  of  a  heavy  coating  of  ice;  and  for  the  same  reason  they  are  not 
found  in  wann  climates.  So  far  as  the  Avrit.  is  aware,  they  have  never 
been  found  in  the  fossil  condition,  except  that  in  a  single  instance  a  series 
of  them  serves  to  record  very  recent  changes  of  level. 

SUBMERGENCK  AND  EMERGENCE. 

In  tlie  preceding  discussion  the  general  relation  of  the  water  surface  to 
the  land  has  been  assumed  to  be  constant.  In  ])oint  of  fact  it  is  subject  to 
almost  continuous  change,  and  its  mutations  motlify  the  products  of  littoral 
shaping. 

Lakes  with  outlet  lower  their  water  surfaces  by  con-ading  the  channel 
of  outflow.  Lakes  without  outlet  continually  oscillate  up  and  down  with 
changes  of  climate;  Jind  finally,  all  large  lakes,  as  well  as  the  ocejin,  are 
aftected  by  differential  movements  of  the  land.  The  series  of  displacements 
which  in  the  geologic  past  has  so  many  times  revolutionized  the  distribution 
of  laud  and  water,  has  not  ceased;  and  earth  movements  are  so  nearly  uni- 
versal at  the  present  time  that  there  are  few  coasts  which  betray  no  sjTnntoms 


THE  COASTS  OF  RISING  AND  SINKING  LANDS.  73 

of  recent  elevation  or  subsidence.  In  this  place  it  is  unnecessary  t(j  consider 
whetlier  the  relation  of  water  snrftxce  to  land  is  affected  by  mutations  of  the 
one  or  of  tlie  otlu-i';  and  the  terms  emergence  and  submergence  will  be  used 
with  the  understanding  tliat  they  apply  to  clianges  in  the  relation  without 
reference  to  causes  of  change. 

Tlie  general  effect  of  submergence  or  emergence  is  to  change  the 
horizon  at  which  shore  ])rocesses  ai'e  carried  on;  and  if  a  considerable 
change  of  level  is  effected  abruptly,  the  nature  of  the  ])rocesses  and  the 
character  of  their  ])roducts  are  not  materially  modified.  A  submerged  shore- 
line retains  its  configuration  until  it  is  gradually  buried  by  sediments.  An 
emerged  shore-line  is  subjected  to  slow  destruction  by  atmospheric  agen- 
cies. Only  the  delta  is  rapidly  attacked,  and  that  is  merely  divided  into 
two  parts  l)y  the  stream  which  formed  it.  In  the  case  of  submergence  the 
new  shore  constructed  at  a  hi^'her  horizon  is  essentially  similar  to  the  one 
submerged.  In  the  case  of  emergence  the  new  shore  constructed  at  a  lower 
horizon  rests  upon  the  smooth  contours  wrought  by  lacustrine  sedimenta- 
tion, and,  finding  in  the  configuration  little  that  is  incongruous  witli  its  shore 
currents,  carves  few  cliffs  and  builds  few  embankments.  The  barrier  is 
usually  one  of  its  characteristic  elements. 

A  slow  and  gradual  submergence  modifies  the  products  of  littoral  action. 
The  erosion  of  sea-cliffs  is  exceptionally  rapid,  because  the  gradually  deep- 
ening water  upon  the  wave-cut  terraces  relieves  the  waves  from  the  task  of 
carving  the  terraces  and  enables  them  to  spend  their  full  force  against  the 
cliffs.  The  cliffs  are  thus  beaten  back  before  the  advancing  tide,  and  their 
precipitous  character  is  maintained  with  constant  change  of  position. 

A  rhythm  is  introduced  in  the  construction  of  embankments.  For  each 
level  of  the  water  surface  there  is  a  set  of  positions  appropriate  to  the  initia- 
tion of  embankments,  and  Avith  an  advancing  tide  these  positions  are  suc- 
cessively nearer  and  nearer  the  land ;  but  with  the  gradual  advance  of  water 
the  position  of  embankments  is  not  correspondingly  shifted.  The  embank- 
ment constructed  at  a  low  stage  controls  the  local  direction  of  the  shore 
current,  even  when  its  crest  is  somewhat  submerged,  and  by  this  control  it 
determines  the  shore  di-ift  to  follow  its  original  course.  It  is  only  when  the 
submergence  is  sufficiently  rapid  to  produce  a  considerable  depth  of  water 


74  LAKE  BONNEVILLE. 

over  the  crest  of  the  embankment  that  a  new  embankment  is  initiated  behind 
it.  The  new  embankment  in  turn  controls  tlie  shore  current,  and  by  a  rep- 
etition of  the  process  a  series  of  embankments  is  produced  whose  crests 
differ  in  height  by  considerable  intervals. 

A  slow  and  gradual  emergence  causes  the  waves,  at  points  of  excava- 
tion, to  expend  their  energies  upttn  the  terraces  rather  than  the  cliffs.  No 
great  cliffs  ui-e  produced,  but  a  wave-cut  terrace  is  carried  downward  with 
the  receding  tide.  Then;  is  now  no  rliytlmi  in  the  construction  of  embank- 
ments. At  each  successive  lower  level  the  shore  drift  takes  a  course  a  little 
farther  lakeward,  and  is  built  into  a  lower  embankment  resting  against  the 
outer  face  of  the  one  just  formed. 

The  delta  is  very  sensitive  to  emergence.  As  soon  as  the  lake  water 
falls  from  its  edge,  the  formative  stream,  having  now  a  lower  point  of  dis- 
charge, ceases  to  throw  down  detritus  and  begins  the  corrasion  of  its  chan- 
nel. It  ceases  at  the  same  time  to  shift  its  course  over  the  surface  of  the 
original  delta,  l)ut  retains  whatever  position  it  happened  to  hold  when  tlie 
emergence  was  initiated.  Coincidently  it  begins  the  constraction  of  a  new 
or  secondary  delta,  the  ajiex  of  wliicli  is  at  the  o^^ter  margin  of  the  original 
structure.  With  continuous  emei'gence  a  series  of  new  deltas  are  initiated 
at  points  successively  farther  lakeward,  and  there  is  pi-oduced  a  continuous 
descending  ridge  divided  by  the  chaimel  of  the  stream. 

THE  DISCRIMINATION  OF  SHORE  FEATURES, 

A  .shore  is  the  common  margin  of  dry  land  and  a  body  of  water.  The 
elements  of  its  peculiar  topography  are  little  liable  to  confusion  so  long  as 
they  are  actually  associated  with  land  on  one  side  and  water  on  the  other; 
but  after  the  water  has  been  withdrawn,  their  recognition  is  less  easy.  They 
consist  merely  of  certain  cliffs,  terraces,  and  ridges;  and  cliffs,  terraces, 
and  ridges  abound  in  the  topography  of  land  surfaces.  In  the  following 
pages  the  topographic  features  characteristic  of  ancient  shores  will  be  com- 
pared and  contrasted  with  other  topographic  elements  likely  to  create  con- 
fusion. 

Such  a  discrimination  as  this  lias  not  before  been  attempted,  although 
the  principal  distinctions  upon  wliich  it  is  based  have  been  the  common 


DISCRIMINATION  OF  SHORE  FEATURKS.  75 

property  of  geologists  for  many  years.  The  contrast  of  stream  terraces  with 
shore  terraces  was  clearly  set  forth  by  Dana  in  the  American  Journal  of 
Science  in  1849,  and  has  been  restated  by  Geikie  in  his  Text-Book  of  Ge- 
ology. It  was  less  clearly  enunciated  by  the  elder  Hitchcock  in  his  Illus- 
trations of  Surface  Geology. 

CLIFFS. 

A  clitf  is  a  tojwgraphic  facet,  in  itself  steep,  and  at  the  same  time  sur- 
rounded by  facets  of  less  inclination.  The  only  variety  belonging  to  the 
phenomena  of  shores  is  that  to  which  the  name  "sea-cliflf "  has  been  ap})lied. 
It  will  be  compared  with  the  cliff  of  differential  degradation,  the  stream  cliff, 
the  coulee  edge,  the  fault  scarp,  and  the  land-slip  cliff. 

The  Cliff  of  Differential  Degradation.-It  is  a  familiar  fjxct  that  cortaiu  rocks,  maiuly 
soft,  yield  more  rajjidly  to  the  agents  of  ei-osion  than  certain  other  rocks, 
mainly  hard.  It  results  from  this,  that  in  the  progressive  degradation  of  a 
country  by  subaerial  erosion  the  minor  reliefs  are  generally  occupied  by 
hard  rocks  while  the  minor  depressions  mark  the  positions  of  soft  rocks. 
Where  a  hard  rock  overlies  one  much  softer,  the  erosion  of  the  latter  pro- 
ceeds so  rapidly  that  the  former  is  sapjjed,  and  being  deprived  of  its  support 
falls  away  in  Ijlocks,  and  is  thus  wrought  at  its  margin  into  a  cliff.  In  re- 
gions undergoing  rajiid  degradation  such  cliffs  are  exceedingly  abundant. 

It  is  the  invariable  mark  of  a  cliff"  oi  differential  degradation  that  the 
rock  of  the  lower  part  of  its  face  is  so  constituted  as  to  yield  more  rapidly 
to  erosion  than  the  rock  of  the  upper  part  of  its  face.  It  is  strictly  dependent 
on  th(!  constitution  and  structure  of  the  terrane.  It  may  have  any  form,  l)ut 
since  the  majority  of  rocks  are  stratified  in  Ijroad,  even  sheets,  and  since  tlie 
most  abrupt  alternations  of  texture  occur  in  connection  with  such  stratifica- 
tion, a  majority  of  cliffs  of  differential  degradation  exhibit  a  certain  uniformity 
and  parallelisin  of  parts.  The  crest  of  such  a  cliff  is  a  line  parallel  to  the 
base,  and  other  associated  cliffs  run  in  lines  approximately  parallel.  The 
most  conspicuous  of  the  cliffs  of  stratified  rocks  occur  where  the  strata  are 
approximately  horizontal;  and  these  more  often  than  any  others  have  been 
mistaken  for  sea-cliffs. 

The  Stream  Cliff. -The  most  powerful  agent  of  land  erosion  is  the  running 
stream,  and,  in  regions  undergoing  rapid  degradation,  corrasion  by  streams 


76  LAKE  BONNEVILLE. 

so  far  exceeds  the  general  waste  of  the  surface  that  their  channels  are  cut 
down  vertically,  forming  cliffs  on  either  hand.  Tliese  cliffs  are  afterward 
maintained  hy  lateral  corrasion,  which  opens  out  the  valley  of  the  stream 
after  the  establishment  of  a  base  level  has  checked  the  vertical  corrasion. 
Such  cliffs  are  in  a  measure  independent  of  the  nature  of  the  rock,  and  are 
closely  associated  with  the  stream.  They  stand  as  a  rule  in  pairs  facing 
each  other  and  separated  only  by  the  stream  and  its  flood  plain.  The  base  of 
each  is  a  line  inclined  in  the  direction  of  the  stream  channel  and  in  the  same 
degree.  The  crest  is  not  parallel  thereto,  l)ut  is  an  uneven  line  conforming 
to  no  simple  law. 

The  Coulee  Edge.-The  viscosity  of  a  lava  stream  is  so  great,  and  this  i-is- 
cosity  is  so  augmented  as  its  motion  is  checked  l)y  gradual  cooling,  that  its 
margin  after  congelation  is  usually  marked  by  a  cliff  of  some  height.  The 
distinguishing  characters  of  such  a  cliff  are  that  the  rock  is  volcanic,  ^\•ith 
the  supei-ficial  features  of  a  subaerial  flow.  It  has  probably  never  been  mis- 
taken for  a  sea-cliff,  and  receives  mention  here  only  for  the  sake  of  giving 
generality  to  the  classification  of  cliffs. 

The  Fault  Scarii.-Tlie  faultiug  of  rocks  consists  in  the  relative  displacement 
of  two  masses  separated  by  a  fissure.  The  plane  of  the  fissure  is  usually 
more  or  less  vertical,  and  by  virtue  of  the  displacement  one  mass  is  made 
to  project  someA^'hat  above  the  other.  The  portion  of  the  fissure  wall  thus 
brought  to  view  constitutes  a  variety  of  cliff  or  escarpment,  and  has  been 
called  a  fault  scarp.  In  the  Great  Basin  such  scai-jis  are  associated  with  a 
great  number  of  mountain  ranges,  appearing  generally  at  their  bases,  just 
where  the  solid  rock  of  the  mountain  mass  is  adjoined  by  the  detrital  foot 
slojie.  They  occasionally  encroach  upon  the  latter,  and  it  is  in  siu-h  case 
that  they  are  most  conspicuous  as  well  as  most  likel}-  to  ])e  mistaken  for 
sea-cliffs.  Although  in  following  the  mountain  bases  tliev  do  not  varv 
greatly  in  altitude,  yet  they  never  describe  exact  contours,  Ijut  ascend  and 
descend  the  slopes  of  the  foot  hills.  Tlie  crest  of  such  a  cliff  is  usually 
closely  parallel  to  the  base  for  long  distances,  but  this  jtarallclism  is  not 
aljsolute.  The  two  lines  gradually  converge  at  either  end  of  the  displace- 
ment. In  exceptional  instances  they  converge  rapidly,  giving  the  cliff  a 
somewhat  abrupt  termination,  and  in  such  case  anew  clifi'ai)pears  en  dchelon, 


COMPARISON  OF  CLIFFS.  77 

continuing  the  displacement  with  a  slight  ofiFset.  In  Chapter  VIII  these 
cliffs  are  described  at  length  and  illustrated  by  views  and  diagrams. 

The  Land-Slip  Cliff. -Tlic  laud-slip  dltfcrs  from  the  fault  chiefly  in  the  fact 
that  it  is  a  purely  superficial  phenomenon,  having  its  Avhole  history  upon  a 
visible  external  slope.  It  occurs  usually  in  unconsolidated  material,  masses 
of  which  break  loose  and  move  downward  short  distances.  The  cliffs  pro- 
duced by  their  separation  from  the  general  or  parent  mass,  are  never  of  great 
horizontal  extent,  and  have  no  common  element  of  form  except  that  they 
are  concave  outward.  They  frequently  occur  in  groups,  and  are  apt  to  con- 
tain at  their  bases  little  basins  due  to  the  backward  canting  which  forms 
part  of  the  motion  of  the  sliding  mass. 

Comparison.  -The  sca-clift"  differs  from  all  others,  first,  in  that  its  base  is 
horizontal,  and,  second,  in  that  there  is  associated  with  it  at  one  end  or  other 
a  beach,  a  barrier,  or  an  embankment.  A  third  valuable  -diagnostic  feature 
is  its  uniform  association  with  the  terrace  at  its  base;  but  in  this  respect  it 
is  not  unique,  for  the  cliff  of  differential  degradation  often  springs  from  a 
terrace.  Often,  too,  the  latter  is  nearly  horizontal  at  base,  and  in  such  case 
the  readiest  comparative  test  is  found  in  the  fact  that  the  sea-cliff  is  inde- 
pendent of  the  texture  and  structure  of  the  rocks  from  Avhich  it  is  carved, 
while  the  other  is  closely  dependent  thereon. 

The  sea-cliff  is  distinguished  from  the  stream-cliff  by  the  fact  that  it 
faces  an  open  valley  broad  enough  and  deep  enough  to  permit  the  genera- 
tion of  efficient  waves  if  occupied  b}-  a  lake.  It  is  distinguished  from  the 
coulee  edge  by  its  independence  of  rock  structure  and  by  its  associated  ter- 
race. It  differs  from  the  fault  scai-p  in  all  those  peculiarities  which  result 
from  the  attitude  of  its  antecedent;  the  water  surface  concerned  in  the  for- 
mation of  the  sea-cliff  is  a  horizontal  plane;  the  fissure  concerned  in  the 
formation  of  the  favilt  scarp  is  a  less  regular  but  essentially  vertical  ])lane. 
The  former  crosses  the  inequalities  of  the  preexistent  topography  as  a  con- 
tour, the  latter  as  a  traverse  line. 

The  land-slip  cliff  is  distinguished  by  the  marked  concavity  of  its  face 
in  horizontal  contour.  The  sea-cliff  is  usually  couA-ex,  or,  if  concave,  its 
contours  are  long  and  sweeping.  The  former  is  distinguished  also  by  its 
discontinuity. 


78  LAKE  BONNEVILLE. 

TERRACES. 

A  terrace  is  a  horizontal  or  nearly  horizontal  topographic  facet  inter- 
rupting a  steeper  slope.  It  is  a  limited  plain,  from  one  edge  of  which  the 
ground  rises  more  or  less  steeply,  while  from  tlie  opjjosite  edge  it  descends 
more  or  less  stee})ly.     It  is  the  "tread"'  of  a  topographic  step. 

Among  the  features  peculiar  to  shores  are  three  terraces :  the  wave-cut, 
the  Avave-built,  and  the  delta.  These  will  be  compai-ed  with  tlie  terrace  by 
differential  degradation,  the  stream  terrace,  the  moraine  terrace,  the  fault 
terrace,  and  the  land-slip  terrace. 

The  Terrace  by  Differential  Degradation.-The    SaUlO     gCUCral    cirCUmStaUCCS    of     Hlck 

texture-  which  nnder  erosion  give  rise  to  cliffs  j^roduce  also  terraces,  but  the 
terraces  are  of  less  frequent  occurrence.  The  only  case  in  which  they  are 
at  all  abundant,  and  the  only  case  in  which  they  need  be  discriminated  from 
littoral  terraces,  is  that  in  which  a  system  of  strata,  heterogeneous  in  texture 
and  lying  nearly  horizontal,  is  truncated,  either  by  a  fault  or  by  some  erosive 
action,  and  is  afterwards  subjected  on  the  truncated  section  to  atraosphei'ic 
waste.  The  alternation  of  hard  and  soft  strata  gives  rise  under  such  cir- 
cumstances to  a  series  of  alternating  cliffs  and  terraces,  the  outcrop  of  each 
hard  stratum  appearing  in  a  more  or  less  vertical  cliff",  and  the  outcrop  of 
each  soft  stratum  being  represented  l)y  a  gently  sloping  terrace,  united  to 
the  cliff  above  by  a  curve,  and,  in  typical  exam})les,  separated  from  the  cliff 
below  by  an  angle. 

The  length  of  such  terraces  in  the  direction  of  the  strike  is  nsuallv  great 
as  compared  with  their  w^idth  from  cliff'  to  cliff.  They  are  never  level  in  cross 
profile,  but  (1)  rise  with  gradually  increasing  slo])efrom  the  crest  of  one  cliff 
to  the  base  of  the  next,  or  (2)  descend  from  the  crest  of  one  cliff'  to  a  medial 
depression,  and  thence  rise  with  gradually  increasing  slope  to  the  base  of  the 
next.  The  first  case  arises  where  the  terrace  is  narrow  or  the  dip  of  the 
strata  is  toward  the  lower  cliff,  the  second  case  where  the  teiTace  is  broad  and 
the  (lip  of  the  rocks  is  toward  the  up})er  cliff.  In  the  first  case  the  drainage 
is  outward  to  the  edge  of  the  lower  cliff;  in  the  second  it  is  toward  the  medial 
depression,  whence  it  escapes  by  Jie  narrow  channels  carved  througli  tlic 
rock  of  the  lower  cliff. 


DEGRADATION  TERRACES.  79 

The  Stream  Terrace.-Tlic'  coiiditioii  of  rapid  crosiou  ill  ally  region  is  u})lift.  In 
a  tract  which  has  recently  been  elevated,  the  rate  of"  degradation  is  iine({ual, 
the  waste  of  the  water  channels  being  more  rapid  than  that  of  the  surface  in 
general,  so  that  they  are  deeply  incised.  Eventually,  however,  the  corrasion 
of  the  water  channels  so  reduces  their  declivities  that  the  velocities  of  current 
suffice  merely  for  the  transportation  outward  of  the  detritus  disengaged  by 
the  general  waste  of  surface.  In  other  words,  a  base  level  is  reached.  Then 
the  process  of  lateral  corrasion,  always  carried  on  to  a  certain  extent,  as- 
sumes jirominence,  and  its  results  are  rendered  conspicuous.  Each  stream 
wears  its  banks,  swinging  from  side  to  side  in  its  valley,  always  cutting  at 
one  side,  and  at  the  other  building  a  shallow  deposit  of  alluvium,  which  con- 
stitutes its  flood  plain.  The  valley,  having  before  consisted  of  the  river 
channel  margined  on  either  side  by  a  clift,  now  consists'  of  a  plain  bounded 
at  the  sides  by  cliffs  and  traversed  by  the  river  channel. 

If  now  the  corrasion  of  the  stream  bed  is  accelerated  by  a  new  uplift 
or  other  cause,  a  smaller  valley  is  excavated  within  the  first  and  at  a  lower 
level.  So  much  of  the  original  flood  plain  as  remains  constitutes  terraces 
flanking  the  sides  of  the  new  valley.  Outwardly  one  of  these  terraces  is 
bounded  by  the  base  of  the  old  line  of  cliffs,  which  may  by  decay  have  lost 
their  vertical  habit.  Inwardly  it  is  bounded  by  the  crest  of  the  new  line  of 
cliHs  i>roduced  by  lateral  corrasion. 

Acceleration  of  downward  corrasion  is  Ijrought  about  in  many  ways. 
As  already  mentioned,  it  may  be  produced  by  a  new  uplift,  and  this  stimu- 
lus is  perhaps  the  most  potent  of  all.  It  is  sometimes  produced  by  the 
downtlirow  of  the  tract  to  which  the  streams  discharge,  or,  \\\\;\t  is  nearly 
the  same  thing,  by  the  degradation  of  stream  channels  in  that  tract.  It  is 
also  brought  about,  within  a  certain  range  of  conditions,  by  increase  of 
rainfall;  and  finally,  it  always  ensues  sooner  or  later  from  the  defect  of 
transported  material.  The  general  waste  of  the  originally  uplifted  tract 
undergoes,  after  a  long  period,  a  diminution  in  rapidity.  The  streams  have 
therefore  less  detritus  to  transport.  Their  channels  are  less  clogged,  and 
they  are  enabled  to  lower  them  by  corrasion.  Perhaps  it  would  be  better 
to  say  that  after  the  immediate  consequences  of  uplift  have  so  far  passed 
away  that  an  equilibrium  of  erosive  action  is  established,  the  degradation  of 


80  LAKE  BONNEVILLE. 

the  entire  tract  proceeds  at  a  slow  continuous  rate,  the  sliglit  variations  of 
whic'h  are  in  a  sense  accidental.  Lateral  corrasion  under  such  circumstances 
coexists  in  all  stream  channels  with  downward  corrasion,  and  is  the  more 
important  process;  but  the  horizon  of  its  action  is  continuously  lowered  by 
the  downward  corrasion.  The  terraces  which  result  represent  onl}-  the 
stages  of  a  continuous  process. 

In  a  great  number  of  stream  valleys,  not  one  but  many  ancient  flood 
plains  find  record  in  terraces,  so  that  the  stream  terrace  is  a  familiar  topo- 
graphic feature. 

When  a  stream  meandering  in  a  flood  plain  encroaches  on  a  wall  of 
the  valley  and  corrades  laterally,  it  carries  its  work  of  excavation  down  to 
the  level  of  the  bottom  of  its  channel;  and  afterward,  when  its  course  is 
shifted  to  some  other  part  of  the  valley,  it  leaves  a  deposit  of  allu\'ium,  the 
upper  surface  of  which  is  barely  submerged  at  the  flood  stage  of  the  stream. 
The  depth  of  alluvium  on  the  flood  plain  is  therefore  measured  by  the  ex- 
treme depth  of  the  current  at  high  water  It  constitutes  a  practically  even 
sheet,  resting  on  the  undisturbed  terrane  beneath.  When  the  stream  finally 
abandons  it,  and  by  carving  a  deeper  channel,  converts  it  into  a  terrace,  the 
terrace  is  necessarily  bipartite.  Above,  it  consists  of  an  even  layer  of  allu- 
vial material,  fine  at  top  and  coarse  at  bottom;  below,  it  consists  of  the 
preexistent  formation,  whatever  that  may  be.  Where  the  lower  portion  is 
so  constituted  as  to  resist  erosion,  it  loses  after  a  long  period  its  alluvial 
blanket,  and  then  the  terrace  consists  simply  of  the  floor  of  hard  rock  as 
pared  away  by  the  meandering  stream.  The  coarse  basal  portion  of  the 
alluvium  is  tlie  last  to  disappear;  and  if  it  contains  Inird  bowlders  some  of 
these  will  sui'vive  as  long  as  the  form  of  the  terrace  is  recognizable. 

The  elder  Hitchcock  enumerated  and  described  four  types  of  stream 
terrace:  the  lateral  terrace,  the  delta  teiTace  (groui)ed  by  the  writer  with 
shoi-e  terraces),  the  gorge  terrace,  and  the  glacis  terrace;'  and  Miller,  whose 
clear  anal}'sis  of  stream  terracing  is  tlie  most  recent  contribution  to  the  sub- 
ject,^ adds  the  ampliitheater  terrace,  the  junction  terrace,  and  the  fan  ter- 
race.    Such  detail  is  not  required  in  this  connection,  but  it  is  proper  to  dis- 

'  Illustrations  of  Surface  Geology.     By  Edward  Hitchcock,     p.  .5. 

'River-Terracing:  its  Methods  and  their  results.    Bj  Hugh  Miller.     In  Proc.  R<iyal  Physical  Soc, 
vol.  7,  1«83,  pp.  263-306. 


STREAM  TERRACES.  81 

tiiio-uish  the  fan  terrace  from  the  lateral  terrace,  to  which  the  phraseology 
of  the  preceding  jjaragraphs  more  particularly  applies. 

The  fan  terrace  of  Miller,  as  developed  in  a  mountain  country,  has  been 
admirably  described  and  figured  by  Drew,  who  speaks  of  it  as  an  "alluvial 
fan  cut  by  a  river",  but  gives  no  shorter  title;'  in  the  nomenclature  of  the 
present  chapter  it  is  an  alluvial-cone  terrace. 

Where  a  large  stream  flowing  through  an  alluvial  plain  receives  a  small 
tributary  from  an  upland  bordering  the  plain,  the  tributary  often  builds 
an  alluvial  cone  upon  the  margin  of  the  plain.  If  afterward  the  large  stream, 
shifting  its  course  over  the  plain,  encroaches  on  the  alluvial  cone,  it  con- 
verts it  into  a  teiTace.  The  small  stream  acquires  in  this  manner  a  lower 
point  of  discharge  and  is  induced  to  corrade  a  channel  through  its  own 
alluvial  cone,  dividing  it  into  two  parts.  With  reference  to  the  valley  of 
the  small  stream,  these  parts  are  lateral  terraces.  With  reference  to  the 
valley  of  the  large  stream,  they  constitute  together  an  alluvial-cone  terrace. 
The  alluvial-cone  terrace  differs  from  the  lateral  terrace  in  that  its  surface 
does  not  incline  uniformly  in  the  direction  of  the  current  of  the  stream  it 
overlooks,  but  inclines  radially  in  all  directions  from  a  point  at  the  side  of 
the  valley. 

The  Moraine  Terrace.- Wlieu  au  alluvlal  plain  OY  alluvial  couc  Is  built  agaliist 
the  side  or  front  of  a  glacier  and  the  glacier  is  afterward  melted  away,  the 
alluvial  surface  becomes  a  terrace  overlooking  the  valley  that  contained 
the  ice.  The  constructing  stream  may  flow  from  the  ice  and  gather  its  allu- 
vium from  the  glacial  debris,  but  it  usually  flows  from  the  land.  The  slope 
of  the  alluvial  plain  is  detennined  by  the  direction  and  other  accidents  of 
the  stream.  Where  the  plain  adjoins  the  glacier,  it  receives  whatever  debris 
falls  from  the  ice,  and  it  may  be  said  to  coalesce  initially  with  a  morainic 
ridge.  Its  internal  constitution  is  partly  alluvial  and  partly  morainic.  If 
the  morainic  ridge  is  large,  the  plain  does  not  become  a  moraine  terrace. 
If  it  is  small,  it  falls  away  when  the  removal  of  the  ice  permits  the  margi 
of  the  plain  to  assume  the  "angle  of  repose." 

'  AUnvial  and  lacustrine  deposits  and  glacial  records  of  the  Upper-Indus  Basin.     By  Fr( 
Drew.     Quart.  Jour.  Geol.  Soc.     London,  vol.  29,  1873,  pp.  441-471, 

^Theallitvialfan  o(  Drew  is  the  alluvial  cone  of  American  geologists,  and  there  would  beUbme 
reasons  for  preferring  fan  to  cone  if  it  were  necessary  to  employ  a  single  term  only.     It  is  conveknent 
to  use  them  as  synonyms,  employing  cone  when  the  angle  of  slope  is  high,  and  fan  when  it  is  low 
MON   I 6 


82 


LAKE  BONNEVILLE. 


2- 


Moraine  teiTacos  may  be  classified,  after  tlic  uianiicr  of  moraines,  as 
lateral  and  troutal.  The  history  of  the  lateral  type  is  illustrated  l)y  V'v^. 
1 7,  representing  in  cross  section  the  side  of  a  glacier  in  an  open  valley.    The 

alluvium,  rt,  is  built  up  syn- 
chronously with  the  glacial 
debris,  f7,  and  the  two  interbed 
and  mingle  at  their  junction. 
When  the  ice  melts,  the  face 
of  the  deposit  assumes  under 
gravity  the  ])rofile  indicated 
by  the  dotted  line. 

If  the   glacier   diminishes 

Fig.  17. -Ideal  section,  illustratiDg  the  formation  of  a  Moraine  Terrace        (rradually,    SUCCeSsive  teiTaCCS 

at  the  Siilo  of  a  GLacier.  * 

are  formed,  and  these  fre- 
quently overlap.  In  P'ig.  18  it  is  assumed  that  the  ice  profile  had  succes- 
sively the  positions  of  the  dotted  lines  x  and  y.  When  it  retreated  to  y,  the  ac- 
cumulated deposit  assumed  the 
profile  ahc,  and  a  new  deposit 
besran  between  the  ice  and  the 
face  ftc.  By  subsequent  ice 
retreat  the  second  deposit  as- 
sumed the  profile  def.  As  a 
result  of  this  process  the  ma- 
terial of  the  terrace  de  overlies 
unconfonnably  the  material  of  the  terrace  db. 

An  alluvial  plain  bordering  the  front  of  a  glacier  is  apt  to  overlap  the 

ice  and  to  include  near  its  outer 
margin  not  only  morainic  debris 
but  blocks  of  ice.     "When  the 


Fig.  18. -Ideal  section,  showing  the  internal  structure  of  gnmpcil 
Lateral  Moraine  Terraces. 


-|—  ice  melts,  the  overlapping  de- 
posit cannot  assume  the  simple 
earth-slope  or  angle  of  repose, 

F,G.  19  _I,l..als.ction„f.Uuvialfin„,ga,..,inst  Front  Edge  of  GLuier.  ^^^    i-gceiveS  a  huimilOcky,    UIO- 

rainic  surface  (Fig.  20). 


MORAINE  TERRACES, 


83 


So  closely  does  the  moraine  terrace  simulate  the  stream  terrace  tliat  it 
is  usually  undistiug-uislied.'  The  lateral  tyi)e  is  identical  in  cross-profile 
and  in  longitudinal  profile,  and, 
unless  portions  of  the  morainic 
ridge  remain,  has  but  one  for- 
mal difference:  the  contours  of 
its  outer  face,  being  determined 
by  the  side  of  an  ice  stream, 
are  smootli  curves  of  gentle  flexure. 

The  Fault  Terrace.-It  somctunes  occurs  that  two  or  more  fault  scarps  with 
throw  in  the  same  direction,  run  parallel  with  each  other  on  the  same  slope, 
thus  dividing  the  surface  into  zones  or  tracts  at  various  heights.  Each  of 
these  tracts  contained  between  two  scarps  is  a  terrace.  It  is  a  dissevered 
section  of  the  once  continuous  general  surface,  divided  by  one  fault  from  that 
which  lies  above  on  the  slope  and  by  another  from  that  which  lies  below.  It 
is  the  top  of  a  diastrophic  block,  and  its  inclination  depends  upon  the  attitude 
of  that  block.  Usually  the  block  is  tilted  in  a  direction  opposite  at  once  to 
that  of  the  throw  of  the  limiting  faults  and  to  that  of  the  general  slope  of  the 
country.  This  has  the  effect  of  giving  to  the  terrace  an  inclination  less  steep 
than  that  of  neighboring  plains,  or  (exceptionally)  of  inclining  it  in  the  oppo- 
site direction. 

In  the  direction  of  its  length,  which  always  coincides  with  the  strike  of 
the  faults,  the  terrace  is  not  horizontal,  but  undulates  in  sympathy  with  the 
general  sui-face  from  which  it  has  been  cut. 

The  Land-Slip  Terrace.-Tliis  is  closcly  related  in  cross-profile  to  the  fault  ter_ 
race,  but  is  less  regular  and  is  of  less  longitudinal  extent.  Its  length  is  fre- 
quently no  greater  than  its  width.  The  surface  on  which  motion  takes  place 
has  a  cross  section  outwardly  concave,  so  that  the  sliding  mass  moves  on  an 
arc,  and  its  upper  surface,  constituting  the  terrace,  has  a  less  inclination 
than  in  its  original  position.  Frequently  this  effect  is  carried  so  far  as  to 
incline  the  terrace  toward  the  cliff  which  overlooks  it,  and  occasionally  the 

'  Its  recognition  was  probably  late.  W.  S.  Green  describes  it  in  "The  Higli  Alps  of  New  Zealand" 
(London,  1883),  and  Chambeilln  describes  and  names  it  in  the  Third  Annual  Report  of  the  U.  S.  Geo- 
logical Survey,  p.  304.  The  name  "  moraine  terrace  "  was  provisionally  attached  by  E.  Hitchcock  (Sur- 
face Geology,  pp.  6,  61)  to  a  phenomenou  not  now  regarded  as  a  terrace. 


84  LAKE  BONNEVILLE. 

edg'e  of  the  terrace  is  connected  with  the  cKflf  in  such  way  as  to  form  a  small 
lake  basin. 

An  even  terrace  of  such  origin  is  rarely  observed.  The  surface  is  usually 
luunmocky,  and  where  slides  occur  in  groups,  as  is  their  habit,  the  hillside 
is  thrown  into  a  billowy  condition  suggestive  of  the  surface  of  a  terminal 
moraine. 

comparison.-The  ouly  fcaturc  by  which  shore  ten'aces  are  distinguished 
from  all  terraces  of  other  origin,  is  the  element  of  horizontality.  The  wave- 
cut  terrace  is  hounded  by  a  liorizontal  line  at  its  uj)per  edge;  the  delta  is 
bounded  l)y  a  horizontal  line  about  its  lower  edge;  and  the  wave-built  ter- 
race is  a,  horizontal  plain.  But  the  application  of  this  criterion  is  rendered 
diflRcult  1)\-  th(^  fact  tliat  the  terrace  of  differential  degi'adatiou  is  not  infre- 
quently margined  l)v  liorizontal  lines;  while  the  inclinations  of  the  stream 
terrace  and  the  moraine  terrace,  though  universal  and  essential  characters, 
are  often  so  small  in  amount  as  to  be  dithcult  of  recognition.  The  fault 
terrace  and  land-slip  terrace  are  normally  so  uneven  that  this  character  suf- 
ficiently contrasts  them  with  all  shore  features. 

The  Avave-cvit  terrace  agrees  A\ith  all  the  non-shore  terraces  in  that  it 
is  overlooked  by  a  cliff  rising  from  its  upper  margin,  and  usuallv  differs  in 
that  it  merges  at  one  end  or  l)oth  with  a  beach,  barrier,  or  embankment.  It 
is  further  distin^'uished  from  the  terrace  of  differential  deo-radation  l)v  the 
fact  that  its  contiguration  is  independent  of  the  structure  of  the  rocks  from 
which  it  is  carved,  while  the  latter  is  closely  dependent  thereon.  In  freshlv 
formed  examples,  a  further  distinction  mav  be  recognized  in  the  mode  of 
junction  of  terrace  and  cliff.  As  viewed  in  protile,  the  wave-cut  terrace 
joins  the  associated  sea-cliff  by  an  angle,  while  in  the  profile  wi-ought  by  dif- 
ferential degradation,  the  terrace  curves  upward  to  meet  the  overlooking  cliff. 

The  wave-cut  terrace  is  distinguished  from  the  stream  terrace  by  tlu' 
fact  that  it  appears  only  on  the  margin  of  an  oi)eu  bnsiu  broad  enough  for 
the  propagation  of  efficient  waves,  whereas  the  latter  usually  margins  a  nar- 
row or  restricted  basin.  In  the  case  of  broad  terraces  a  further  thstinction 
is  found  in  the  fact  that  the  shore  terrace  descends  gently  from  its  cliff  to  its 
outer  margin,  whereas  the  stream  terrace  is  normally  level  in  cross  section. 
In  fresh  examples  the  alluvial  capping  of  the  stream  terrace  affords  addi- 
tional means  of  discrimination. 


COMPARISON  OF  TERRACES,  85 

The  wave-cut  terrace  is  distiuguislied  from  the  moraine  terrace  by  the 
fact  that  its  floor  consists  of  the  preexistent  terrane  in  situ,  the  moraine  ter- 
race being  a  work  of  construction.  The  wave-cut  terrace  occurs  most  fre- 
quently on  saHents  of  the  topography;  its  inner  margin  is  a  simpler  curve 
than  its  outer.  The  moraine  terrace  is  found  most  frequently  in  reentrants; 
its  outer  margin  is  a  simpler  curve  than  its  inner. 

There  are  certain  cases  in  which  the  wave-formed  and  stream  terraces 
merge  with  each  other  and  are  difficult  of  separation.  These  occur  in  the 
estuaries  of  ancient  lakes,  where  the  terraces  referable  to  wave  action  are 
confluent  with  those  produced  contemporaneously  by  the  lateral  corrasion 
of  streams.  The  stream  being  then  tributary  to  the  lake,  it  could  not  carry 
its  erosion  to  a  lower  level,  and  its  zone  of  lateral  corrasion  was  at  its  mouth 
continous  with  the  zone  of  wave  erosion  in  the  lake. 

The  wave-built  terrace  may  be  distinguished  from  all  others  Ijy  the 
character  of  its  surface,  which  is  corrugated  with  ])arallel,  curved  ribs.  It 
differs  from  all  except  stream  and  moraine  terraces  in  its  material,  which  is 
wave-rolled  and  wave-sorted.  It  diff'ers  from  the  stream  terrace  in  that  it 
stands  on  a  slope  facing  an  open  basin  suitable  for  the  generation  of 
waves. 

The  delta  differs  from  all  except  the  stream  terrace  and  the  moraine 
terrace  in  its  material  and  in  its  constant  relation  to  a  water  way.  Its  mate- 
rial is  that  known  as  stream  drift.  Its  mass  is  alwa}'s  divided  by  a  stream 
channel  so  as  to  lie  partly  on  each  bank ;  its  terminal  contour  is  a  convex 
arc  centering  on  some  point  of  the  channel ;  and  it  is  usuall}'  confluent  in 
the  ascending  direction  with  the  normal  stream  terrace.  Indeed,  when  con- 
sidered with  reference  to  the  dividing  channel,  it  is  a  stream  terrace ;  and  it 
is  only  with  reference  to  the  lakeward  margin  that  it  is  a  shore  terrace.  It 
is  distinguished  from  the  normal  stream  terrace  by  its  internal  structure. 
The  high  inclination  of  the  lamination  of  its  middle  member — formed  by  the 
discharge  of  coarse  detritus  into  standing  water — is  not  shared  by  the  stream 
terrace,  while  its  horizontal  alluvium  does  not,  as  in  the  case  of  the  stream 
terrace,  rest  on  the  preexistent  terrane.  It  is  distinguished  from  simulating 
phases  of  the  moraine  terrace  by  its  outer  contour,  which  is  outwardly  con- 
vex and  more  or  less  in-egular,  while  that  of  the  moraine  terrace  is  straight 


86  LAKE  BONNEVILLE. 

or  simply  curved.  The  frontal  moraine  terrace  often  affords  a  further  dis- 
tinction by  the  hummocky  character  of  its  outer  face. 

As  the  formation  of  the  delta  is  independent  of  wave  action,  it  may 
and  does  take  place  in  sheltered  estuaries  and  in  small  basins.  A  small 
lake  interrupting  the  course  of  the  stream  may  be  completely  filled  by  the 
extension  of  the  delta  built  at  its  upper  extremity ;  and  when  this  has 
occurred,  there  is  nothing  in  the  superficial  phenomena  to  distinguish  the 
foi'mation  from  the  normal  flood  plain. 

The  terrace  of  diff'erential  degradation  is  further  distinguished  from  all 
shore  teri'aces  by  the  fact  that,  without  great  variations  in  width,  it  follows 
the  turnings  of  the  associated  cliff,  conforming  to  it  in  all  its  salients  and 
reentrants.  Where  the  shore  follows  an  irregular  contour,  wave-cut  ter- 
races appear  only  on  the  salients,  and  in  the  reentrants  only  wave-built 
terraces  and  deltas. 

RIDGES. 

Ridges  are  linear  topographic  reliefs.  They  may  be  broadly  classed 
into  (1)  those  produced  by  the  erosion  or  dislocation  of  the  earth's  surface, 
and  (2)  those  built  uj)()n  it  Ijy  superficial  transfer  of  matter.  In  the  first 
class,  the  substance  of  the  ridge  is  continuous  with  that  of  the  adjacent  plain 
or  valley  ;  in  the  second,  it  is  not ;  and  this  difference  is  so  obvious  that  shore 
ridges,  which  fall  within  the  second  class,  are  not  in  the  least  lialjle  to  be 
confused  with  ridges  of  the  first  class.  They  will  therefore  be  compared  in 
this  place  only  with  other  imposed  ridges.  Of  shore  phenomena,  the  bar- 
rier, the  embankment,  and  the  rampart  are  ridges.  They  will  be  contrasted 
with  the  moraine  and  the  osar. 

The  Moraine— The  dctritus  dcposited  by  glaciers  at  their  lateral  and  termi- 
nal margins  is  usualh'  l)uilt  into  ridyes.  Tlu^  material  of  these  is  fraff- 
mental,  heterogeneous,  nnd  unconsolidated.  It  includes  large  blocks,  often 
many  tons  in  weight,  and  these  are  angular  or  subangular  in  form.  Some- 
times their  surfaces  are  striated.  The  crest  of  the  moraine  is  not  liorizontal, 
but  descends  with  the  general  descent  of  the  land  on  wliich  it  rests. 

Moraines  are  found  associated  with  mountain  valleys,  and  also  upon 
open  plains.  In  the  first  case  their  ci'ests  are  narrow,  and  their  contours 
are  in  general  reorular.      The  lateral  moraines  follow  the  sides  of  the  val- 


COMPARISON  OF  RIDGES.  87 

leys,  often  standing  at  a  considerable  height  above  their  bottoms,  and  are 
united  by  the  frontals  or  terminals,  which  cross  from  side  to  side  witli 
curved  courses  whose  convexities  are  directed  down  stream.  The  moraines 
of  plains  have  bi'oad,  billowy  crests  abounding  in  conical  hills  and  in  small 
basins. 

The  osar  or  Kame.-Tliese  uaines  are  applied  to  an  indirect  product  of  glacial 
action.  It  is  multifarious  in  form,  being  sometimes  a  hill,  sometimes  a  ridge, 
and  often  of  more  complicated  form.  It  doubtless  embraces  types  that  need 
to  be  separated;  but  it  is  here  sufficient  to  consider  only  the  linear  form. 
As  a  ridge,  its  trend  is  usually  in  the  direction  of  glacial  motion.  Its  ma- 
terial is  water-worn  gravel,  sand  and  silt,  with  occasional  bowlders.  Its 
contours  are  characteristically,  but  not  invariably,  irregular.  Its  crest  is 
usually,  but  not  invariably,  uneven;  when  even,  it  is  parallel  to  the  base  or 
to  that  upon  which  the  base  rests.  In  other  words,  the  ridge  tends  to 
equality  of  height  rather  than  to  horizontality. 

Comparison. -The  sliorc  ridges  are  primarily  distinguished  from  the  glacial 
ridges  l)y  the  element  of  horizontality.  The  barrier  and  the  emljankment 
are  level-topped,  while  the  rampart  has  a  level  base  and  is  so  low  tliat  the 
inequality  of  its  crest  is  inconsiderable.  It  is  only  in  exceptional  cases  and 
for  short  distances  that  moraines  and  osars  exhibit  horizontality.  Shore 
ridges  are  further  distinguished  by  their  regularity.  Barriers  and  embank- 
ments are  especially  characterized  by  their  smoothness,  while  smooth  osars 
are  rare,  and  tlie  only  moraine  with  even  contours  is  the  lateral  moraine  • 
associated  with  a  narrow  valley. 

Other  means  of  discrimination  are  afforded  by  the  component  materials, 
and  tlie  moraine  is  thus  clearly  differentiated.  The  barrier  and  the  embank- 
ment consist  usually  of  sand  or  iine  gravel,  from  which  both  clay  and  larger 
boAvlders  have  been  eliminated.  Except  in  immediate  proximity  to  the  sea- 
cliff  whose  erosion  affords  the  detritus,  the  pebbles  and  bowlders  are  well 
I'ounded.  The  material  of  the  rampart  has  no  special  qualities,  but  is  of 
local  derivation,  the  ridge  being  formed  simply  by  the  scraping  together  of 
superficial  debris.  The  moraine  contains  heterogeneous  material  ranging 
from  fine  clay  to  very  large,  angular  blocks.  The  materials  of  the  osar  are 
normally  less  rounded  than  those  of  normal  shore  ridges. 


88  LAKE  BONNEVILLE. 

Certain  osars  of  great  length,  even  figure,  and  uniform  lieight  are  dis- 
tinguished from  barriers  by  the  greater  declivaty  of  their  flanks,  and  by  the 
fact  that  they  do  not  describe  contoiu's  on  the  margins  of  Ijasins. 

THE    RECOGNITION    OF    ANCIENT    SHORES. 

The  facility  and  certainty  with  which  tlie  vestiges  of  ancient  water 
margins  are  recognized  and  traced  depend  on  local  conditions.  The  small 
waves  engendered  in  ponds  and  in  sheltered  estuaries  are  far  less  efficient 
in  the  carving  of  cliifs  and  the  construction  of  embankments  than  are  the 
great  waves  of  larger  water  bodies ;  and  the  faint  outlines  they  produce  are 
afterward  more  difficult  to  trace  than  those  strongly  drawn. 

The  element  of  time,  too,  is  an  important  factor,  and  this  in  a  double 
sense.  A  water  surface  long  maintained  scores  its  shore  mark  more  deeply 
than  one  of  brief  duration,  and  its  history  is  by  so  much  the  more  easily 
read.  On  the  other  hand,  a  system  of  shore  topography  from  which  the 
parent  lake  has  receded,  is  immediately  exposed  to  the  obliterating  influence 
of  land  erosion,  and  gradually,  though  very  slowly,  loses  its  character  and 
definition.  The  strength  of  the  record  is  directly  proportioned  to  the  dura- 
tion of  the  lake  and  inversely  to  its  antiquity. 

It  will  be  recalled  that  in  the  preceding  description  the  character  of 
horizontality  has  been  ascribed  to  every  shore  feature.  The  base  of  the 
sea-clitf  and  the  coincident  margin  of  the  wave-cut  terrace  are  hoi'izontal; 
and  so  is  the  crest  of  each  beach,  barrier,  embankment,  and  wave-built 
terrace;  and  the}'  not  merely  agree  in  the  fact  of  horizontality,  but  fall 
essentially  into  a  common  plane — a  plane  intimately  related  to  the  horizon 
of  the  maximum  force  of  breakers  during  storms.  The  outer  margin  of  the 
delta  is  likewise  horizontal,  but  at  a  slightly  lower  level — the  level  of  the 
lake  surface  in  repose.  This  diff"erence  is  so  small  that  for  the  purpose  of 
identification  it  does  not  affect  the  practical  coincidence  of  all  the  horizontal 
lines  of  the  shore  in  a  single  contour.  In  a  region  where  forests  aft'ord  no 
obstruction,  the  observer  has  merely  to  bring  his  eye  into  the  plane  once  oc- 
cupied by  the  water  surface,  and  all  the  horizontal  elements  of  shore  topog- 
raphy are  projected  in  a  single  line.  This  line  is  exhibited  to  him,  not 
merely  by  the  distinctions  of  light  and  shade,  but  by  distinctions  of  color, 


VALUE  OF  THE  DISTANT  VIEW.  89 

due  to  the  fact  that  the  changes  of  inclination  and  of  soil  at  the  line  influence 
the  distribution  of  many  kinds  of  vegetation.  In  this  manner  it  is  often 
possible  to  obtain  from  the  general  view  evidence  of  the  existence  of  a  faint 
shore  tracing,  which  could  be  satisfactorily  determined  in  no  otlier  way. 
The  ensemble  of  a  faintly  scored  shore  mark  is  usually  easier  to  recognize 
than  any  of  its  details. 

It  is  proper  to  add  that  this  consistent  horizontality,  wliich  appeals  so 
forcibly  and  effectually  to  the  eye,  can  not  usually  be  verified  by  instru- 
mental test.  The  surface  of  the  "solid  earth"  is  in  a  state  of  change, 
whereby  the  vertical  relations  of  all  its  parts  are  continually  modified. 
Wherever  the  surveyor's  level  has  been  applied  to  a  fossil  shore,  it  has  been 
found  that  the  "horizon"  of  the  latter  departs  notably  from  horizontality, 
being  warped  in  company  with  the  general  surface  on  whicli  it  rests.  The 
level,  therefore,  is  of  little  service  in  the  correlation  of  shore  lines  seen  at 
different  places  and  not  continuously  traced;  but  when  an  ancient  shore-line 
has  been  faithfully  traced  through  a  basin,  the  determination  by  level  of  its 
variations  in  height  discovers  the  nature  of  displacements  occurring  since 
its  formation.  It  might  appear  that  the  value  of  horiz(intality  as  an  aid  to 
the  recognition  of  shores  is  consequently  vitiated,  but  such  is  not  the  case. 
It  is,  indeed,  true  that  the  accumulated  warping  and  faiilting  of  a  long 
period  of  time  will  so  incline  and  disjoint  a  system  of  shore  features  that 
they  can  no  longer  be  traced;  but  it  is  also  true  that  the  processes  of  land 
erosion  will  in  the  same  time  obliterate  the  shore  features  tlieniselves.  The 
minute  elements  of  orographic  dis{)lacement  are  often  paroxysmal,  but  so 
far  as  observation  informs  us,  the  genei'al  progress  of  such  changes  is  slow 
and  gradual,  so  that,  during  the  period  for  which  shore  tracings  can  with- 
stand atmospheric  and  pluvial  waste,  their  deformation  is  not  sufficient  to 
interfere  materially  with  their  recognition. 


CHAPTER    III. 

SHORES  OF  LAKE  BONNEVILLE. 

In  the  preceding  chapter  the  features  of  a  single  desiccated  shore-line  are 
described;  a  shore-hne,  that  is,  with  nothing  above  it  on  the  shaping  side  of 
its  basin  except  the  varied  topography  characteristic  of  dry  hind,  and  noth- 
ing below  it  but  the  smooth  monotony  of  a  lake  bottom.  Proceeding  now 
to  the  consideration  of  the  Bonneville  shores,  we  pass  from  the  simple  to  the 
complex,  for  the  Bonneville  Basin  is  girt  by  many  shore-lines,  which  form  a 
continuous  series.  Only  the  highest  of  these  is  contiguous  to  land  topog- 
raphy, and  only  the  lowest  encircles  an  area  covered  exclusively  by  lake 
sediments.  The  water  has  undergone  changes  of  volume  wliicli  have  car- 
ried its  surface  and  waves  to  every  part  of  the  basin  from  the  bottom  to  an 
altitude  of  1,000  feet.  So  much  of  the  basin  as  lies  below  the  highest  shore- 
line has  received  lake  sediments;  and  the  geologic  data  comprised  in  these 
sediments  are  combined  with  the  phenomena  of  the  lower  beaches  in  a  man- 
ner that  is  at  once  instructive  and  complicated.  The  superpositions  of  shore- 
line upon  lake  sediment  and  lake  sediment  u])on  shore-line  record  a  history 
of  contracting  and  expanding  lake  area,  the  deciphering  of  which  constitutes 
one  of  the  chief  subjects  of  our  study.  These  will  be  discussed  at  length  in 
the  sequel.  Here  it  is  desired  merely  to  state  the  foct  that  for  a  vertical 
space  of  1,000  feet  on  the  sides  of  the  liasin,  the  evidences  of  lacustrine 
waves  and  lacustrine  sedimentation  have  been  iraposeil  oii  tlic  preexistent 
cimfiguration  of  tlie  countrv. 

Lake  Bonneville  lay  in  the  district  of  the  Basin  Ranges,  and  the  whole 
configuration  of  tlie  land  al)ove  the  shore-lines  is  of  the  Basin  Range  \\\>e. 
Asdescrilx'd  in  tlie  introductory  chapter,  that  district  is  studded  with  a  -great 


EARLIER  SCULPTURE  SUBAEKIAL.  91 

number  of  small  mountain  ranges,  standing  in  irregular  order,  but  with  a 
nearly  constant  north-south  trend.  BetAveen  them  are  narrow  valleys  Hoored 
by  detritus  worn  from  their  summits  during  the  uncounted  ages  of  their 
existence.  At  the  foot  of  each  range,  and  piled  high  against  its  sides,  are 
great  conical  heaps  of  alluvium,  each  with  its  apex  at  a  mountain  gorge. 
At  top  these  alluvial  cones  are  separate,  but  lower  down  they  adjoin,  and 
their  bases  coalesce  into  a  continuous  scolloped  slope,  the  visible  footstool 
of  the  mountain.  The  cones,  like  the  valley  floors,  are  composed  of  detritus 
eroded  from  the  mountains,  but  their  material  is  coarser.  At  the  margins 
of  the  undrained  valleys  the  cones  merge  by  gentle  curvature  with  the 
valley  floors.  In  the  higher  valleys,  which  drain  to  the  closed  basins, 
cones  from  the  two  sides  meet  along  the  medial  line,  giving  to  the  cross 
profile  the  form  of  an  obtuse  \y-  Above  the  alluvial  cones  all  is  of  solid 
rock,  and  the  topographic  forms  are  hard  and  angular.  Every  water-pai-ting 
is  a  sharp  ridge,  and  every  water-way  is  an  acutely  V-shaped  gorge. 

The  ridge  and  the  gorge  are  characteristic  features  of  land  sculpture, 
being  carved  only  where  rain  and  running  water  serve  for  erosive  tools. 
The  alluvial  cone  is  an  equally  characteristic  land  feature,  being  formed 
only  where  running  water  throws  down  detritus,  without  itself  stopping. 
They  are  all  the  distinctive  and  exclusive  products  of  land  shaping,  and 
could  never  originate  beneath  a  lake  or  ocean. 

These  are  the  features  exhibited  by  the  Bonneville  Basin  above  the 
highest  shore-line;  and  the  same  features  can  be  traced  continuously  down- 
ward past  the  shore-line  and  to  the  bottoms  of  the  once  submerged  valleys. 
If  one  stands  at  a  distance  and  views  the  side  of  a  valley,  lie  will  see  that 
each  of  the  great  alluvial  cones  is  traceable  within  the  zone  of  submergence 
almost  as  distinctly  and  quite  as  surely  as  above  it.  Its  curving  contour 
formed  a  part  of  every  individual  shore  of  the  series.  So,  too,  of  the  moimt- 
ain  gorges  and  ridges;  wherever  they  extend  below  the  ancient  water  limit 
the  shore-line  can  be  seen  to  follow  their  contours  in  a  manner  demonstrat- 
ing that  they  were  already  in  existence  when  the  lines  were  drawn. 

The  preexistent  topography  of  the  Bonneville  Basin  was  therefore  of 
terrestrial  type  and  of  subaerial  origin.  The  sea-cliff's  and  embankments 
and  sediments  of  the  lake  were  carved  from  and  built  on  and  spread  o^•er  a 


92  LAKE  BONNEVILLE. 

system  of  reliefs  which  originated  at  a  time  anterior  to  the  hike,  when  the 
(h-ainao-e  of  the  mountains  descended  without  obstruction  to  the  bottoms 
of  the  valleys.  In  this  respect,  and  in  other  respects  to  be  developed  further 
on,  the  pi-e-Bonneville  conditions  were  identical  with  the  post-Bonneville. 

Illustrations  of  this  general  fact  could  be  adduced  almost  witliout  limit, 
for  they  are  aifoi'ded  by  all  the  slopes  of  the  basin,  but  a  few  will  suffice. 

In  Plate  VIII  there  appears  at  the  right  a  jiortion  of  the  western  front 
of  the  Frisco  Range.  The  crowded  and  uneven  contour  lines  mark  the  posi- 
tion of  steep-faced  rock  undergoing  erosion.  At  the  foot  of  the  range  is  a 
system  of  alluvial  cones,  represented  by  contours  with  smooth  curves  and 
regular  spaces.  Still  lower  are  the  contours  produced  by  wave  action,  and 
lowest  of  all  is  the  outline  of  a  playa.  A  moment's  attention  will  show  that 
the  great  alluvial  cone  at  a,  which,  like  a  trunk  glacier,  is  compounded  at 
its  head  of  a  number  of  single  cones,  is  represented  at  the  base  of  the 
slope  by  the  convexity  at  c.  The  cone  h  appears,  though  less  plainly,  at  f; 
and  the  cone  d  appears  at  /(.  The  cone  c  is  greatly  disguised  at  g,  being 
loaded  with  a  group  of  embankments;  Ijut  it  is  jjrobable  that  it  has  liad 
something  to  do  with  the  deflection  of  shore-currents  whereby  those  em- 
bankments were  originated.  Conversely,  the  indentation  at  j  represents  tlie 
uiibroken  rock-face  at  i,  where  for  a  space  of  half  a  mile  no  debris-convey- 
ing srorffe  issues  from  the  mountain;  and  the  dearth  of  detritus  in  the  remon 
A-  is  represented  by  the  indentation  at  /.  The  maj)  also  suggests,  what  a 
study  of  the  ground  demonstrates,  that  the  material  built  into  embankments 
was  derived  by  the  paring  away  of  the  coast  to  the  north  f)f  each  locality  of 
deposit.  Considered  by  themselves,  the  monuments  of  the  waves'  activity 
are  by  no  means  inconsiderable;  each  grou])  of  embankments  contains 
some  hundi'eds  of  millions  of  cubic  yards  of  gravel;  but  they  sink  into  insig- 
nificance when  compared  with  the  stupendous  monuments  of  alluvial  activ- 
ity on  which  they  rest.  They  are  mere  appendages,  and  the  erosion  of 
their  material  from  the  adjacent  slopes  has  by  no  means  oljliterated,  though 
it  lias  somewhat  defaced,  the  alluvial  forms. 

Granite  Rock,  an  isolated  mountain  of  the  Salt  Lake  Desert,  has  at  its 
north  end  a  gorge  dividing  the  extremity  into  two  narrow  spurs.  About 
these  spurs  the  Bonneville  waters  rose  to  a  height  several  hundred  feet 


U.S. GEOLOGICAL    SUPVET 


LAKE  BONNEVILLE      PL  Vm 


.luhus  BuMi  AC..,hil, 


Drown  bv  (•  Tb'impttnD 


LAND  SHAPING  BEFORE  SHOKE  SHAPING.  93 

above  any  alluvial  accumulation.  All  about  the  .spurs  there  is  a  distinct 
terrace  cut  in  the  granite  at  the  highest  water  level,  and  the  same  can  be 
traced,  less  continuously  but  still  unmistakably,  along  the  sides  of  the 
gorge  to  its  head.  This  relation  could  not  subsist  had  not  the  gorge  and  the 
sj)urs  been  carved  out  in  substantially  their  pi-esent  form  before  the  Avaves 
attacked  them. 

Bradley,  speaking  of  the  canyon  of  Ogden  River,  says  : 

It  is  evident  that,  when  this  canyou  was  originally  excavated,  the  Great  Salt  Lake 
was  not  far,  if  at  all,  above  its  present  level ;  so  that  the  rushing  torrent  which  wore  out 
this  old  rounded  bottom  met  no  check  until  it  had  passed  entirely  beyond  the  mouth  of 
thecanyon.  There  followed  a  time  when  the  lake  tilled  nearly  or  quite  to  its  highest  ter- 
race; and,  meanwhile,  the  Ogtleii  River  continued  to  bring  down  the  sand  and  pebbles 
which  it  had  before  been  accustomed  to  sweep  out  upon  the  lower  terrace,  but  now, 
checke<l  by  the  rising  lake,  deposited  them  in  the  lower  parts  of  its  old  channel,  until 
they  accumulated  to  a  very  high  level,  not  yet  accurately  located.  Again,  the  lake 
retired,  and  the  stream  again  cut  down  its  channel,  sometimes  reaching  its  old  level 
and  sometimes  not.' 

In  each  of  these  localities  the  subaerial  work  antecedent  to  the  lake 
epoch  has  greatly  exceeded  in  amount  the  lacustrine  work ;  and  the  last 
has  in  like  manner  exceeded  the  subaerial  work  subsequent  to  the  lake 
epoch.  Disregarding  the  rate  at  which  the  several  processes  are  carried  on, 
it  is  evident  that  the  construction  of  the  alluvial  cones  of  Frisco  Mountain 
is  a  greater  work  than  the  building  of  the  embankments  that  ornament  their 
flanks ;  while  the  preservation  of  the  embankments  shows  that  little  alluvial 
accumulation  has  since  been  made.  The  carving  of  the  spurs  and  gorge  at 
Granite  Rock  implies  the  decay  and  removal  of  cubic  miles  of  granite,  while 
the  production  of  the  shore  terrace  involved  the  excavation  of  only  a  few 
thousand  yards  of  the  same  rock. 

THE    BONNEVIIiLiE    SHOKE-IilNE. 

The  shore-lines  of  the  series  in  the  Bonneville  Basin  are  not  of  uniform 
magnitude.  The  water  rose  and  fell  step  by  step,  but  not  with  equal  pace, 
and  at  a  few  stages  it  lingered  much  longer  than  at  others,  giving  its  waves 
time  to  elaborate  records  of  exceptional  prominence.  One  of  the  excep- 
tional records  is  that  which  holds  the  highest  position  on  the  slopes ;  and  to 

'  U.  S.  Geol.  Surv.  of  Terr.,  Ann.  Kept,  for  1872,  p.  196. 


94  LAKE  BONNEVILLE. 

tliis  one,  par  excellenro,  tlie  name  Bonneville  has  been  applied.  It  marks 
tlie  greatest,  expanse  of  the  ancient  lake,  and  tonus  the  boundary  of  the 
area  of  lacnstrine  phenomena.  . 

Above  the  Bonneville  shore-line  the  whole  aspect  is  that  of  the  dry 
land — here,  an  alternation  of  acutely  cut  water  partings  and  water  ways; 
there,  huge,  rounded  piles  of  alluvium;  the  first  stream-carved,  the  last 
stream-built;  and  each  presenting  to  the  eye  a  system  of  inclined  prf)files. 
Below  the  shore-line,  the  same  oblique  lines  are  to  be  found,  but  with  them 
are  an  abundance  of  horizontal  lines,  wrought  by  the  waves  at  lower  levels — 
the  terraces,  beaches,  barriers,  and  embankments  of  lower  shore-lines. 

Except  in  sheltered  bays,  where  the  waves  had  little  force,  and  except 
on  smooth,  mural  clifts  of  rock,  where  a  beach  could  not  cling  and  where 
the  waves  were  impotent  for  lack  of  erosive  tools,  the  contrast  between  wave 
work  and  stream  work  is  strong,  and  the  line  separating  the  two  types  of 
earth-shaping  is  easily  traced.  If  the  Bonneville  shore-line  were  far  less 
deeply  engraved  than  it  is,  it  would  still  be  conspicuous  by  reason  of  its 
position.  As  it  is,  no  geologic  insight  is  necessary  to  discover  it,  for  it  is 
one  of  the  pronounced  features  of  the  country.  It  confronts  all  beholders 
and  insists  on  recognition.  The  tourist  who  visits  Ogden  and  Salt  Lake 
City  by  rail  sees  it  on  the  Wasatch  and  on  the  islands  of  Great  Salt  Lake, 
and  makes  note  of  it  as  he  rides.  The  farmer  who  tills  the  valley  below  is 
familiar  with  it  and  knows  it  A^as  made  by  water;  and  even  the  coAV-boy, 
finding  an  easy  trail  along  its  terrace  as  he  "rides  the  range",  relieves  the 
monotony  of  his  existence  by  hazarding  a  guess  as  to  its  origin. 

The  altitude  of  the  Bonneville  shore-line  is  about  1,000  feet  above  Great 
Salt  Lake  and  al)Oiit  5,200  feet  above  the  ocean.  In  defining  it  as  the 
highest  shore  of  the  basin,  I  have  assumed  the  correctness  of  the  more 
prevalent  view  of  a  mooted  question ;  but  before  proceeding  farther  the  op- 
posing view  shovild  be  considered. 

THE   QUESTION   OF  A   HIGHER   SHORE-LINE. 

It  has  been  announced  by  Peale^  that  there  is  evidence  of  a  Pleistocene 
lake  in  the  BonneAalle  Basin  with  a  water  level  from  300  to  600  feet  above 
the  Bonneville  shore-line,  or  from  ,''),r)00  to  5,800  feet  above  the  sea.     "On 

>  The  AnciuDt  Outlet  of  Great  Salt  Lake.  By  A.  C.  Peale,  Am.  Jour.  Sci.,  3d  series,  vol.  15,  1878, 
pp.  439-444. 


A  DISCREPANCY  OF  OBSERVATION.  95 

both  sides  of  the  Portneuf  where  it  comes  into  Marsh  Creek  Valley  an 
upper  terrace  is  seen,  and  in  1872  Prof.  ¥.  11.  Bradley  also  readily  identi- 
fied an  upper  terrace  in  the  Marsh  Creek  Valley  at  the  level  of  about  1,000 
feet  above  the  stream.  In  Gentile  Valley  and  in  Cache  Valley  also,  traces 
of  this  upper  terrace  exist."  In  the  })assage  referred  to,^  Bradley  mentions 
this  terrace  in  connection  with  stream  terraces,  but  does  not  speak  definitely 
of  its  origin.  Its  interpretation  as  a  shore  feature  therefore  rests  with  Peale, 
who  regards  it  as  identical  with  the  one  observed  by  him  "on  both  sides  of 
the  Pt»rtneuf "  It  has  not  been  seen  by  me,  but  I  am  by  no  means  sure 
that  in  seeking  it  I  succeeded  in  following  Bradley's  route.  With  more  con- 
fidence it  may  be  asserted  that  Marsh  Valley  is  not  contoured  by  any  well- 
marked  shore-line.  I  was  careful  to  study  its  slopes  from  stations  at  various 
levels  and  under  favorable  atmospheric  conditions,  and  I  failed  to  discover 
even  the  faintest  trace  of  wave  work.  The  same  careful  search  was  made 
for  high-level  shore  traces  in  Cache  Valley  and  Gentile  Valley,  but  none 
were  found.  There  are  indeed  terraces  in  Gentile  Valley,  and  these  are 
elsewhere  mentioned  by  Peale,  who  found  their  altitudes  5,526,  5,242  and 
5,186  feet;^  but  they  are  stream  terraces,  not  shore  terraces. 

It  is  with  reluctance  that  I  record  not  only  my  inability  to  rediscover 
phenomena  which  another  has  reported,  but  also  my  opinion  that  his  reported 
discovery  was  based  on  an  error  of  observation ;  but  the  question  here  in- 
volved is  of  such  importance  in  its  relation  to  the  Bonneville  history  that  it 
can  not  well  be  ignored. 

As  set  forth  in  the  second  chapter,  there  are  various  other  types  of  ter- 
races liable  to  be  mistaken  for  shore  terraces ;  and  the  ranging  of  shore  ter- 
races and  other  wave-wrought  features  in  the  same  horizontal  line,  or  })lane, 
is  a  characteristic  of  great  imjjortance  in  their  discrimination.  To  the  ob- 
server who  places  himself  in  that  plane  and  views  the  distant  hillside  at  his 
own  level,  certain  elements  of  the  various  shore  features  appear  united  in  a 
horizontal  line.  If  he  selects  for  his  observation  an  hour  when  the  distribu- 
tion of  lights  and  shadows  gives  strong  expression  to  the  details  of  the  con- 
figuration, he  is  able  to  detect  a  shore  record  so  fjiint  that  he  might  cross 
and  recross  it  repeatedly  without  suspecting  its  existence.     Having  searched 

'  Rept.  U.  S.  Geol.  Survey  Terr,  for  l>-82,  pp.  20a-'203. 

^Eept.  U.  S.  Geol.  Survey  Terr,  for  1877,  Washington,  1879,  p.  001. 


96  LAKE  BONNEVILLE. 

with  distant  view  and  selected  light  for  the  reported  high-level  shore  traces 
in  Marsh  and  ( "ache  Valleys,  and  having  failed  to  discover  them,  I  am  satis- 
fied that  Peale  misinterpreted  terraces  formed  in  some  other  Avay. 

The  matter  is  not  fnlly  set  forth  l)y  the  recital  of  the  conflicting  obser- 
vations. T\w  Valley  of  Marsh  Creek  falls  outside  not  only  the  Bi)uneville 
Hasin  l)ut  tlic  (Jreat  Basin.  It  is  di'ained  to  the  great  plain  of  the  Snake 
River  by  a  deep  and  rather  broad  canyon  which  bears  the  marks  of  antitj- 
uity.  The  sides  of  this  canyon,  though  of  crystalline  and  schistose  rf)cks, 
are  not  steep,  and  at  the  most  constricted  point  there  is  a  flood-plain  a  tliou- 
sand  feet  broad.  If  there  was,  as  Peale  supposes,  a  barrier  at  this  point 
containing  the  ancient  lake,  then  its  cutting  must  have  consumed  a  long 
period;  and  it  is  incredible  that  shore  terraces  have  survived  the  contem- 
])oraneous  general  waste  of  the  surface.  If  there  was  no  barrier  at  this  point, 
then  the  supposed  lake  was  a  great  inland  sea,  flooding  the  plain  of  the  Snake 
River,  and  its  shore  tracings  on  the  margins  of  that  plain  should  have  been 
much  more  conspicuous  (by  reason  of  the  greater  magnitude  of  its  waves) 
than  any  drawn  in  Marsh  Valley, — but  they  have  not  been  discovered. 

Moreover,  a  body  of  Avater  capable  of  fomaing  the  supposed  shore  ter- 
races in  Marsh  Valley  would  have  extended  not  only  to  Cache  and  Gentile 
Valleys  1)ut  to  the  Great  Salt  Lake  Desert,  and  the  work  of  its  waves  should 
be  visible,  if  anywhere,  (m  the  face  of  the  Wasatch  Range.  In  tliat  region, 
the  conditions  for  the  generation  of  large  waves  are  far  more  favorable  than 
in  the  relatively  narroAv  valley  of  Marsh  Creek.  Nevertheless,  a  higher  line 
has  not  been  observed  on  the  margin  of  the  greater  basin.  Not  only  has 
Peale  failed  to  record  it  there,  but  Bradley,  Howell,  Emmons,  Hague,  and 
King  have  expressly  noted  the  BonncAnlle  as  the  highest  shore-line.^ 

It  may  be  objected  that  the  failure  of  these  numerous  observers  to  de- 
tect an  upper  shore-line  is  negative  evidence  merely,  and  should  be  given 
little  weight  in  comparison  Avith  a  single  positi\'e  obser\-ation.  But  the  fail- 
ure to  detect  is  in  this  case  something  more  than  a  negation.  Subaerial  land 
sculpture  is  as  positive  a  fact  as  AvaA-e-Avrought  shore  sculpture;  and  the  as- 

'  F.  H.  Bradle.y,  U.  S.  Geol.  Surv.  of  Terr.  Ann.  Rept.  1872,  p.  192  E.  E.  Howell,  U.  S.  Geol.  Snrv. 
West  of  the  100th  Meridian,  vol.  3,  Geology,  p.  2r)0.  S.  F.  Emmons,  U.  S.  Geol.  Esplor.  -lOth  Parallel, 
vol.  2,  Descriptive  Geology,  p.  441.  Arnold  Hague,  Idem.  pp.  421,  428.  Clarence  King,  U.  S.  Geol. 
Explor.   40th  Parallel,  vol.  1.    Systematic  Geology,  p.  491. 


U.  S.  GEOLOGICAL  SURVEY 


LAKE  BOXNEJVILLE  PLATE  IX. 


THE  GREAT  BAR  AT 


STOCKTON.  UTAH. 


NEGATIVE  EVIDENCE.  97 

sertion  that  the  Bonneville  is  the  highest  shore-line  implies  the  assertion  that 
above  it  the  topography  is  of  the  ordinary  dry  land  type.  Every  recogni- 
tion of  an  ancient  shore  is  based,  consciously  or  unconsciously,  on  an  ac- 
quaintance with  the  ordinary  cliaracteristics  of  the  features  of  the  land  as 
well  as  with  the  peculiarities  of  shores;  and  ability  to  discriminate  the  pres- 
ence of  wave  sculpture  implies  in  the  same  degree  ability  to  note  its  absence 
and  its  limits.  The  supremacy  of  the  Bonneville  shore  has  been  recognized 
not  only  by  many  observers  Init  in  a  great  number  of  localities,  and  an  induc- 
tion resting  on  so  broad  a  basis  may  justly  demand  of  a  conflicting  obser- 
vation the  most  rigorous  verification. 

K  the  reader  will  turn  to  Plate  IX  he  will  be  able  to  realize  the  weight 
of  this  evidence.  The  view  presents  the  Bonneville  shore  at  the  pass  be- 
tween Tooele  and  Rush  Valleys.  The  observer  stands  on  the  west  side  of 
the  pass  and  looks  eastward  toward  the  Oquirrh  Mountains.  At  the  left 
lies  Tooele  Valley,  open  to  the  main  body  of  the  old  lake.  At  the  right  is 
Rush  Valley,  which  held  a  sheltered  bay.  The  greatest  waves  came  from 
the  north,  and,  beating  on  the  southeast  shore  of  Tooele  Bay,  carved  out  a 
long  line  of  sea-clififs.  The  debris  was  at  the  same  time  drifted  southward 
part  of  it  being  built  into  a  free  spit  7,000  feet  long  and  150  feet  high  at  the 
extremity,  and  another  part  being  accumulated  during  lower  stages  of  the 
lake  in  an  immense  bay-bar,  obstructing  the  pass.  The  spit  appears  in  the 
picture  at  the  right,  following  the  base  of  the  mountain.  The  bay-bar 
extends  from  the  center  of  the  view  to  the  foreground.  It  will  be  observed 
that  the  line  of  sea-cliff  at  its  most  distant  point  impinges  on  a  spur  of  the 
mountain;  and  at  its  southern  end,  near  the  middle  of  the  picture,  it  touches 
another  spur,  while  in  the  interval  it  crosses  only  the  alluvial  slope.  There 
could  scarcely  be  a  greater  contrast  than  between  the  sculi)turing  of  the 
mountain-spurs  above  the  line  of  sea-cliffs  and  the  smooth  contours  of  the 
slopes  below  that  level.  The  cliffs  are  here  of  rather  unusual  height,  and 
the  shore  emliankments  are  of  exceptional  magnitude,  so  that  the  separation 
between  subaqueous  and  subaerial  topography  is  more  than  ordinarily  dis- 
tinct. This  fact  does  not  weaken  the  evidence  that  the  Bonneville  shore-line 
is  the  highest,  but  gives  it  greater  strength.  For,  if  the  water  had  occupied 
a  higher  level  in  Pleistocene  time,  the  waves  would  have  been  able  to  record 

MON   I 7 


98 


LAKE  BONNEVILLE. 


it  at  tliis  jxtiut  l)y  a  shore-line  of  unmistakable  definition.  If  shore  traces  of 
a  greater  lake  are  anywhere  preserved  they  should  lie  found  at  such  a  point 
as  this,  where  the  conditions  for  wave  beating  are  exceptionally  favorable. 
The  same  lesson  maybe  learned  fnmi  Fiiiun'  21,  mikI  fnuii  tlu*  views  on 


I'lu.  "Jl— BuiiiiL'Ville  and  Intermediate  ( nibunknieuts  near  W,  Ilsville,  Utah.  siinwiUji  contrast  betueeu  Lilturul  .iiid 

Subaerial  Topo*:rapliy. 

Plates  XXI  and  XXII,  representing  the  shore  topography  and  mountain 
topography  at  Wellsville  and  Dove  Creek. 


MORE  ANCIENT  LAKES. 

Although  Peale's  supposed  discovery  is  unverified,  and  though  it  is 
believed  that  an  exhaustive  investigation  would  prove  it  to  be  illusory,  it  is 
nevertheless  true  that  some  or  all  of  the  mountains  of  the  Bonne^^lle  Basin 
were  girt  by  shore-lines  long  before  the  Bonneville  epoch,  and  that  if  these 
shore-lines  wei'e  extant  they  would,  in  some  places  at  least,  lie  higher  than 
the  Bonneville.  The  mountains  against  which  Lake  BouncA'ille  washed  are 
relatively  very  old,  so  old  that  they  were  greatly  eroded  before  Tertiary 
tiiiie.  Ever  since  their  first  u})lifting  they  have  been  wasted  by  erosion, 
and  during  at  least  a  portion  of  the  tune  the  detritus  worn   from  them  has 


TERTIAKY  LAKES  OF  TDE  BONNEVILLE  BASIN.  99 

been  received  by  the  interjacent  valleys.  The  degradation  of  tlieir  crests 
and  the  burial  of  their  bases  would  long  ago  have  obliterated  them  had  they 
not  been  preserved  by  a  series  of  supplementary  upliftings,  which,  like  the 
original,  were  ditferential,  not  being  shared  by  the  intervening  valleys.  In 
the  region  of  the  Great  Salt  Lake  Desert,  where  a  plain  has  been  formed 
by  the  coalescence  of  many  valleys  and  the  local  burial  of  the  ranges,  the 
depth  of  detritus  must  be  several  miles.  Of  the  constitution  of  this  depos- 
ited mass  nothing  is  known  by  direct  observation.  It  is  smoothly  covered 
by  the  sediments  of  Lake  Bomieville,  and  no  section  is  exposed.  But  indi- 
rectly we  are  shown  that  some  ])art  of  the  debris  was  spread  under  water, 
for  the  uprising  mountain  ranges  have  carried  with  them  here  and  there, 
clinging  to  their  flanks,  small  patches  of  lacustrine  strata.  It  is  believed 
that  four  separate  groups  of  lake  beds  have  been  thus  distinguished.  The 
first  of  these  occurs  in  the  southeastern  part  of  the  basin,  and  probably 
touches  the  shore  of  the  ancient  lake  only  in  the  estuary  of  the  Sevier 
River.  No  fossils  have  been  found  at  that  point,  but  there  is  little  reason 
to  doubt  that  the  strata  were  once  continuous  with  the  Pink  Cliff  formation, 
which  covers  large  areas  farther  east,  and  has  been  classed  as  early  Eocene. 
The  principal  locality  of  the  second  is  the  eastern  base  of  the  Ombe  Range, 
where  an  isolated  outcrop  of  barren  strata  resting  against  the  mountain 
dips  abruptly  beneath  the  later  sediments  of  the  desert.  These  strata  have 
been  correlated  on  lithologic  grounds  Avith  fossiliferous  beds  farther  west, 
and  are  regarded  by  the  geologists  of  the  Fortieth  Parallel  Survey  as  of 
Middle  Eocene  age.  The  third  group,  though  yielding  no  fossils,  is  believed 
to  be  Neocene.  It  was  first  noted  by  Emmons  in  Rush  Valley  south  of  the 
Great  Salt  Lake  Desert,  and  has  since  been  found  at  the  narrows  of  the 
Jordan  River,  at  Salt  Lake  City,  at  the  north  edge  of  the  desert  near  Matlin, 
and  at  the  extreme  northwest  cornei'  of  the  basin  in  Cache  Valley,  whence 
it  extends  across  the  rim  of  the  basin  into  Marsh  Creek  Valley.  The  strata 
of  the  fourth  group,  known  chiefly  from  the  investigations  of  King  and  Hay- 
den  and  their  assistants,  occur  at  a  number  of  points  along  the  northern 
margin  of  the  plain,  and  are  believed  to  appear  also  north  of -the  divide  in 
districts  now  draining  to  the  Snake  River.  From  Morgan  Valley  to  Cache 
Valley  they  occupy  a  trough  between  two  divisions  of  the  Wasatch  Range. 


100  LAKE  BONNEVILLE. 

On  the  low  northward  continuation  of  the  main  Wasatch  ridge,  where  it 
separates  Cache  and  Malade  Valleys,  they  are  seen  to  be  wrapped  around  a 
series  of  low  crags  of  Paleozoic  rocks ;  and  it  is  evident  tliat  they  liave 
been  raised  to  their  present  prominent  position  by  tlie  reliftiug  of  an  ancient 
crest.  On  the  east  side  of  it  they  have  been  upturned  by  the  displacement 
so  as  to  dip  at  a  high  angle  beneath  the  Bonneville  lacustrine  beds  of  Cache 
Valley.  On  the  west  they  are  separated  from  theii-  original  continuation 
beneath  Malade  Valley  by  a  fault,  the  tlirow  of  which  is  probably  more  than 
1,000  feet.  Their  relation  to  tlie  third  group  has  not  been  established, 
and  it  is  possible  that  they  constitute  a  part  of  the  same  series.  The  local- 
ity of  the  fifth  group  is  just  north  of  Salt  Lake  City,  wliere  an  epaulette  of 
Tertiary  gravel  and  sand  rests  on  a  jutting  shoulder  of  the  Wasatch  Range. 
This  fragment  is  completely  surrounded  by  faults,  its  eastern  continuation 
having  been  lifted  high  in  air  and  obliterated  by  erosion,  and  its  prolonga- 
tion in  every  other  direction  having  been  dropped  so  lo\\-  that  it  is  at  once 
preserved  and  concealed  by  the  deposits  of  the  plain.  This,  too,  is  unfos- 
siliferous ;  and  it  is  here  assigned  to  the  upper  Neocene  merely  on  the 
strength  of  its  structural  relations.  It  is  needless  to  enter  upon  these  at 
this  place ;  l)ut  it  should  be  remarked  that  the  same  relations,  considered 
from  another  point  of  view,  led  King  to  sunnise  its  Eocene  age. 

Each  of  these  lakes  made  its  contribution  to  the  filling  of  the  basin, 
receiving,  sorting,  and  spreading  the  debris  from  the  wasting  mountains; 
but  neither  can  in  strictness  be  called  the  predecessor  of  Lake  Bonneville, 
for  neither  was  confined  to  the  area  of  the  Pleistocene  basin.  So  far  as  in- 
dicated by  observed  outcrops,  the  oldest  Eocene  lake  lay  almost  entirely 
outside  the  Bonneville  area;  and  it  may  have  existed  at  a  time  when  the 
greater  part  of  that  area  was  dry  land.  The  second  stretched  westward  far 
beyond  the  present  drainage  of  the  Salt  Lake  Desert,  and  may  have  over- 
lapped the  Bonneville  Basin  but  slightly.  The  third  and  fourth  encroached 
northward  on  the  drainage  of  the  Columliia  River.  Too  little  is  kuowu  of 
the  fifth  to  indicate  its  relation  to  the  Bonneville  Basin. 

Their  record  is  exceedingly  fragmentary,  but  if  it  were  full  it  would 
still  give  an  hnperfect  history  of  the  basin  in  Tertiary  time,  for  there  is  no 
reason  to  believe  that  they  represent  more  than  a  small  imrt  of  that  time 


NO  TERTIARY  SHORE-LINES.  101 

They  tell  iis,  however,  that  the  physical  mutations  of  the  period  included 
numerous  local  elevations  and  depressions,  whereby  the  di'ainage  of  the 
country  was  repeatedly  revolutionized;  it  was  dry  land  at  one  time  and 
and  lake  basin  at  another.  It  is  quite  possible  that  the  lakes  were  excep- 
tional phenomena,  and  that  the  prevailing  condition  was  one  in  which  the 
whole  area  drained  to  the  ocean.  It  is  equally  possible  that  the  Bonneville 
Basin  continuously  held  a  lake  which,  as  the  land  rose  and  fell  unequally, 
was  expanded  and  contracted,  now  in  one  direction,  now  in  another. 

The  character  of  the  lake  beds  and  their  relations  to  the  mountains, 
show  in  numerous  localities  that  the  ranges  were  not  submerged.  Waves 
must  therefore  have  beaten  on  their  flanks,  and  tlie  cliffs,  terraces,  and  em- 
bankments peculiar  to  shores  must  have  been  wrouglit,  but  of  these  there 
is  no  known  vestige.  When  the  structure  of  the  mountains  has  been  elabo- 
rately studied,  so  that  those  elements  of  their  configuration  which  depend 
on  the  distribution  of  strata  and  on  faults  can  be  definitely  indicated,  it  may 
be  possible  to  point  out  dissected  terraces  and  ruined  sea-clifts  as  remnants 
of  Neocene  shores;  but  for  the  present  such  vestiges  are  beyond  recognition. 
A  shore  is  of  the  most  perishable  of  geologic  phenomena.  It  is  little  more 
than  a  congeries  of  forms ;  and  whether  worn  away  by  atmospheric  agencies 
or  buried  by  sedimentation,  it  ceases  to  lie  available  as  evidence  of  a  water 


margin. 


OUTLINE  OF  THE  LAKE. 


The  outline  of  Lake  Bomieville  at  its  highest  stage  was  intrioate.  Its 
shores  presented  a  succession  of  promontories  and  deep  bays,  and  it  was 
beset  with  islands.  Its  longer  diameter  lay  north  and  south,  parallel  to  the 
trend  of  the  mountain  ranges  of  the  district  and  to  nearly  all  the  lines  of 
geologic  structure.  Its  general  outline  was  rudely  pear-shaped,  with  the 
stem  ])ointing  southward.  A  straggling  series  of  promontories  and  islands 
crossed  it  near  the  middle,  dividing  it  into  two  principal  bodies,  of  which 
the  northern  and  Inrger  covered  the  Great  Salt  Lake  Desert,  and  the  south- 
ern the  Sevier  Desert.  The  long  southward  bay  representing  the  stem  of 
the  pear,  occupied  the  Escalante  Desert.  The  main  body  was  joined  to 
the  Sevier  body  by  three  straits,  of  which  the  deepest  and  broadest  lay  be- 


102  LAKE  BONNEVILLE. 

tween  Simpson  Mountain  at  the  east  and  Mt-Dowell  Mountain  at  the  west, 
in  the  r('(i;i()n  now  known  as  the  Old  River  Bed.  The  EscaUinte  Bay  was 
connected  with  the  Sevier  body  ))y  a  long  strait,  most  constricted  at  Tlier- 
mos  S])ving. 

The  following  details  are  of  local  rather  than  general  interest,  l)ut  are 
essential  to  a  full  description  of  the  lake.  They  will  be  more  readily  fol- 
lowed by  the  aid  of  the  large  map  accompanying  the  volume. 

The  trend  of  the  ranges  gave  character  to  all  the  major  details  of  the 
coast,  and  the  axes  of  the  larger  islands,  ])eninsulas,  and  bays  lay  approxi- 
mately north  and  south.  Beginning  at  the  north  to  describe  them,  we  have 
first  Cache  Valley  bay,  an  oblong  sheet  of  Avater,  tangent  at  one  side  to  the 
main  l)ody  and  there  joined  to  it  by  a  broad  strait  interrupted  by  several 
islands.  Inside  the  bay  were  three  islands,  whose  positions  are  now  marked 
by  Franklin,  Cache,  and  Battle  Creek  buttes.  The  butte  near  Smithfield 
was  likewise  an  island  at  first,  though  finally  connected  with  the  land  by  a  bar. 
The  canyons  of  Bear,  Cub,  Logan,  and  Blacksmith  rivers  were  occupied  by 
inlets,  and  the  Bear  River  inlet  may  have  reached  at  first  to  Gentile  vallcA'. 
These  were  all  gradually  diminished  by  the  deposits  from  the  sti-eams,  and 
eventually  the  Bear  River  inlet  was  approximately,  and  the  Logan  com- 
pletely, filled. 

Malade  Valley  held  a  long  liay  running  northward  from  the  main  bod}', 
and  having  an  expansion  where  the  towns  of  Malade  and  Samaria  now 
stand.  Parallel  but  smaller  bays  occupied  the  Pocatello  and  Blue  Spring 
valleys  and  the  valleys  containing  Hanzel  Spring  and  the  town  of  Snows- 
ville.  Park  Valley  was  filled  by  a  bay,  exceptional  in  its  east  and  west 
trend,  and  separated  from  the  main  body  by  a  group  of  islands.  The  Prom- 
ontory range  was  divided  by  a  strait  at  the  point  where  it  is  crossed  by  the 
Central  Pacific  Railroad,  the  north  j)art  being  a  peninsula  and  the  south  a 
narrow,  rocky  island. 

Little  Mountain,  near  the  town  of  Corinne,  Avas  a  small  island,  and  the 
mountain  from  which  Hanzel  Spring  issues  made  a  group  of  islands.  There 
were  three  small  islands  near  the  site  of  Kelton,  and  one  just  south  of  Ter- 
race. The  Ombe  range,  including  Pilot  Peak,  was  an  island,  sheltering 
behind   it   a  bay  or  sound   from  wliich   a   narrow   arm   ran    northward   to 


DETAILS  OF  ANCIENT  GEOGRAPHY.  103 

Thousand   Spring  Valley,  the  extreme  limit  of  the  water  in   a   northwest 
direction. 

Of  the  existing  islands  of  Great  Salt  Lake,  Stansbury  and  Antelope 
were  islands  then,  and  Fremont  barely  showed  its  apex  above  water.  Of 
the  "lost  mountains"  of  Great  Salt  Lake  Desert,  nearly  all  overtopped  the 
flood.  Silver  Islet,  Newfoundland,  Terrace  Mountain,  Lakeside  Mountain, 
Granite  Rock,  and  a  half-dozen  nameless  buttes,  were  circled  by  rocky 
and  inhospitable  coasts,  but  the  Cedar  Range  west  of  Skull  Valley  made  a 
broad  and  low  island,  which,  bleak  and  barren  as  it  now  is,  we  may  picture 
as  then  mantled  with  verdure. 

The  eastern  shore  of  the  main  body  followed  the  steep  base  of  the 
Wasatch  Mountains,  and  had  a  simple  outline  except  at  three  points,  Avhere 
it  was  diversified  by  the  estuaries  of  Box  Elder  Creek,  Ogden  River,  and 
Weber  River.  The  Box  Elder  estuary  extended  nearly  or  quite  to  the  little 
mountain  valley  where  the  Danish  settlement  of  Mantua  lies.  Ogden 
Canyon  was  occupied  by  a  long  and  narrow  strait,  conuuunicating  with  a 
bay  several  miles  broad,  hemmed  in  by  mountains.  Through  the  canyon 
of  the  Weber  a  similar  strait  connected  the  main  Ijody  of  the  lake  with  a 
small  bay  in  Morgan  valley, — a  bay  on  which  the  Weber  delta  gradually 
encroached,  but  wliich  was  not  completely  obliterated  before  the  final 
subsidence  of  the  water. 

The  western  shore  of  the  main  body  followed  the  eastern  base  of  the 
Gosiute  range,  and  was  characterized  by  an  abundance  of  small  islands.  Its 
only  estuary  ran  southward  a  short  distance  into  Deep  Creek  Valley,  stop- 
ping several  miles  north  of  the  settlement. 

Southward  from  the  main  body  ran  four  long  bays,  two  associated  with 
the  east  shore  and  two  with  the  west.  The  first  of  these,  counting  from  the 
east,  was  divided  by  a  close  stricture  into  an  outer  bay  and  an  inner,  the 
outer  covering  the  valley  of  the  Jordan  River  and  the  inner  spreading  over 
Cedar,  Utah,  and  Goshen  valleys  and  a  part  of  Juab  Valley.  In  the  inner 
bay  the  Goshen  Hills  made  two  islands,  and  the  Pelican  Hills  constituted 
one  large  and  several  small  islands.  Small  estuaries  occiipied  Emigration 
and  Little  Cottonwood  canyons,  connecting  with  the  outer  bay,  and  the 
inner  bay  sent  an  estuary  into  Provo  Canyon.     The  shalloAV  arm  in  Juab 


104  LAKE  BONNEVILLE. 

Valley  was  nearl}'  closed  by  one  of  the  Goshen  islands.  It  connected  by 
the  canyon  of  Salt  Creek  with  the  division  of  the  bay  in  Cjoslien  \'al]('y, 
and  by  the  j)ass  followed  by  the  Utah  Southern  Eailroad  with  the  l)ay 
in  Utah  Valley. 

The  second  of  the  southward  stretchin<i-  liays  was  similarly  constricted, 
its  outer  and  ojx'ii  jiortion  covering  Tooele  Valley,  and  its  inner,  Rush  Val- 
ley. The  two  were  nearly  dissevered  by  the  formation  of  a  wave-liuilt  Ijar 
at  Stockton. 

The  third  bay  occiipied  White  Valley,  a  barren  plain  between  the  Con- 
fusion Range  and  the  liigh  part  of  the  House  Range.  Its  entrance  was  ob- 
structed by  a  rocky  island  consisting  of  the  northern  part  of  the  House 
Range,  and  a  long,  crooked  arm  extending  southward  lacked  little  of  com- 
municating with  a  southerly  division  of  the  lake  and  converting  the  main 
part  of  the  House  Range  into  an  island. 

The  fourth  bay  occupied  Snake  Valley  and  was  long  and  shallow,  turn- 
ing eastward  at  its  southern  extremity. 

The  Confusion  Range  east  of  Snake  Valley,  and  the  House  Range  east 
of  White  Valley,  were  massive  peninsulas,  joined  at  their  southern  extrem- 
ities to  the  western  shore  of  the  lake.  A  corresponding  great  peninsula  on 
the  east  side  was  constituted  by  the  Oquirrh,  Aqui,  Simpson,  Cherry  ("reek, 
and  Tintic  mountains  and  their  dependencies,  and  had  a  greater  area  than 
the  State  of  Delaware.  These  peninsulas,  together  with  the  grou]i  of  islands 
lying  between  them,  separated  the  main  body  of  the  lake  from  tlie  SeA'ier 
body.  The  group  of  islands  comprised  two  of  large  size  and  about  twenty 
of  small  size.  The  largest  island  was  ccmstituted  by  the  Dugway  Range 
and  its  southward  prolongation.  Drum  Mountain;  the  second,  l)y  the 
McDowell  Mountains. 

With  the  Sevier  body  were  connected  two  long  bays  nmning  south- 
ward and  a  number  of  sinaller  ones  indenting  the  eastei'u  and  northeast 
ern  coast.  Of  the  northern  bays,  one  received  the  water  of  Judd  Creek 
and  another  that  of  Cherry  Creek.  A  third,  occupying  Tintic  valley,  was 
more  constricted  at  the  mouth  and  contained  islands.  A  land-locked  bay 
received  the  water  of  the  Sevier  RiA'er  and  was  partially  tilled  by  delta 
deposits.     It  was  connected  with  the  open  lake  by  a  narrow  passage  through 


SIZE  OF  THE  LAKE.  105 

the  Canyon  Range,  comparable  with  the  passage  of  the  Hudson  through  the 
Higlilands. 

Of  the  soiTthern  bays,  the  shorter  and  more  open  occupied  Sevier  I^ake 
Valley  and  Preiiss  Valley.  The  longer  was  narrow  and  irregular,  filling 
the  valley  of  Beaver  Creek  from  George's  ranch  to  Minersville,  and  extend- 
ing thence  southwestward  into  the  Escalante  Desert,  where  it  was  shallow. 
Its  total  length  was  about  one  hundred  miles. 

The  largest  island  of  the  Sevier  body  was  constituted  Ijy  the  Beaver 
Range,  or  Beaver  Creek  Range,  which  was  separated  by  a  narrow  and  tor- 
tuous strait  frc>m  a  peninsular  tract  bearing  the  Frisco  and  Picacho  Mountains. 
There  were  two  low  islands  a  few  miles  broad  close  to  the  western  shore, 
near  Antelope  Spring.  The  apex  of  Fumarole  Butte  was  slightly  emergent, 
and  so  was  tlie  highest  point  of  the  contiguous  lava  naesa.  Small  islands 
marked  the  sites  of  Pavant  and  Kanosh  buttes,  and  there  were  four  rocky 
islands  near  the  mouth  of  Escalante  Bay,  one  of  which  is  now  represented 
by  the  more  northerly  of  the  Twin  Buttes.  In  Escalante  Bay  there  were  five 
or  six  islands. 

EXTENT    OF    THE    LAKE, 

The  area  of  the  Bonneville  water  surface  was  19,750  square  miles,  a 
magnitude  ranking  it  with  the  Laurentian  lakes.  A  fifth  part  of  this  belonged 
to  the  Sevier  body  with  its  dependencies,  and  the  remainder  to  the  main 
body.  Its  length,  measured  in  a  direct  line  from  Cache  Bay  to  the  south  end 
of  Escalante  Bay,  was  346  miles,  and  its  extreme  width,  from  the  mouth  of 
Spanish  Fork  Canyon  to  a  point  on  the  Shoshone  Range  near  Dondon  Pass, 
was  145  miles.  If  its  water  surface  were  given  a  circular  shape,  its  circum- 
ference would  be  500  miles,  but  the  actual  length  of  coast,  exclusive  of  isl- 
ands, was  2,550  miles.  Its  maximum  depth  was  about  1,050  feet.  The  fol- 
lowing table  will  enable  the  reader  to  compare  these  dimensions  with  the 
corresponding  dimensions  of  Great  Salt  Lake  and  the  Laurentian  lakes.' 

'  The  area  of  Lake  Bonneville  wa.s  me.asured  by  I.  C.  Russell ;  the  areas,  lengths,  and  widths  of 
the  Laurentian  lakes,  by  A.  C.  Lane.  The  length  of  a  lake  wa.s,  for  this  purpose,  defined  to  be  the 
length  of  the  longest  straight  line  terminated  by  two  points  of  the  lake  shore;  its  width,  the  greatest 
distance  between  shores  iu  a  direction  at  right  auglo  to  the  hue  of  the  leugth. 


106 


LAKE  BONNEVILLE. 


Tablk  I.     Dimensions  of  Lakes. 


Bonneville. 

Great  Salt. 

Superior. 

Haron. 

23,  800 
247 
215 
702 

Michigan. 

Erie.           Ontario. 

Area  in  aqnare  milea 

19, 750 

346 

145 

1,050 

•2. 170 

83 

51 

f49 

31.. 500 

377 

170 

1,008 

22, 300 
330 
106 
870 

9,900 

246 

58 

210 

7,250 

197 

67 

738 

Width  in  miles  

Extreme  depth  in  feet 

*  In  1869 ;  near  high  stage.  t  At  high  stage. 

The  greater  part  of  the  desiccated  bed  is  an  irreclaimaljle  desert,  liut 
its  eastern  edge  is  the  granary  of  the  Great  Basin.  The  Bear,  the  Weber, 
the  Jordan,  the  Sevier,  and  other  tributaries,  fed  by  the  snow-banks  of  a 
score  of  mountain  ranges  and  plateaus  at  the  east,  carry  their  hfe-giving 
moisture  to  the  genial  climate  of  the  lowlands,  and  a  belt  of  oases  is  the 
result.  If  the  water  were  to  rise  again  to  its  old  mark,  more  than  one  hun- 
dred towns  and  villages  would  be  submerged  and  120,000  persons  would  be 
di'iven  from  their  homes.  The  Mormon  temple  at  Salt  Lake  City  would 
stand  in  850  feet  of  water,  and  the  temple  at  Logan,  the  metropolis  of 
Cache  Valley,  would  stand  in  500  feet  of  water.  Fort  Douglas  would  be 
covered  to  a  depth  of  150  feet,  Ogden  850,  Provo  650,  Kelton  1,000. 

Seven  hundi-ed  miles  of  railroad  would  be  immersed,  and  trans-conti- 
nental passengers  would  be  transferred  by  boat  either  from  Morgan  City  or 
from  Spanish  Fork  to  some  point  near  Toano,  Nevada, — a  voyage  of  145 
miles  for  the  northern  route  or  185  miles  for  the  southern.  The  town  of 
Fillmore  would  be  half  covered,  the  State  House  barely  remaining  on  di-y 
land,  and  Mantua,  Paradise,  Morgan,  and  Minersville  would  be  lake  ports. 
Heramon,  Bingham,  Opliir,  Vernon,  and  Frisco  would  be  peninsular  towns ; 
and  the  mining  settlements  of  Drum  and  Buell  would  be  stranded  on  islands. 

SHORE    DETAILS. 

The  sinuosity  of  the  coast  and  its  diversity  of  slope  and  material  give 
to  the  shore  phenomena  the  utmost  variety.  Every  typical  feature  of  non- 
tidal  shores  is  well  illustrated,  and  some  of  the  combinations  are  perhaps 
unique. 

The  abundance  of  salients  and  reentrants,  of  promontories  and  inlets, 
has  occasioned  a  large  number  of  spits  and  bay  bars,  while  long  beaches 
and  liarricrs  are  rare. 


SEA-CLIFFS  OF  BONNEVILLE  SHORE.  107 

At  an  early  stage  of  the  investigation,  the  writer  thought  that  the 
coasts  facing  in  certain  directions  gave  evidence  of  exceptional  amounts  of 
wave  work,  and  imagined  that  he  had  discovered  therein  the  record  of  prev- 
alent westerly  winds  or  westerly  storms  in  ancient  times.  This  belief  was 
dissipated  by  further  study ;  and  he  discovered,  as  students  of  modern 
shores  long  ago  discovered,  that  there  is  a  close  sympathy  between  the 
magnitude  of  the  shore  features  and  the  "fetch"  of  the  efficient  waves. 
The  greater  the  distance  through  which  waves  travel  to  reach  a  given  coast, 
the  greater  the  work  accomplished  by  them.  The  highest  cliffs,  the  broad- 
est terraces,  and  the  largest  embankments  are  those  wrought  by  the  unob- 
structed waves  of  the  main  body ;  and  opposite  coasts  appear  to  have  been 
equally  affected. 

The  most  interesting  details  of  the  upper  shore-line  are  found  at  locali- 
ties where  similar  details  affect  the  lower  shore-lines,  and  it  will  be  conven- 
ient to  describe  them  in  discussing  the  order  of  succession  of  the  shores ; 
but  certain  features  should  be  mentioned  here.  The  greatest  sea-cliffs  are 
as  a  rule  carved  from  headlands  and  from  the  islands  of  the  main  body,  but 
the  highest  of  all  occurs  in  the  Jordan  Bay  at  a  locality  known  as  the  Point 
of  the  Mountain.  For  a  distance  of  half  a  mile  the  cliff  there  has  an  aver- 
age height  of  one  thousand  feet,  the  eroded  material  having  been  swept 
to  the  southwestward  and  built  into  a  magnificent  spit,  around  the  extrem- 
ity of  which  the  Utah  Southern  Railroad  winds  in  passing  from  Draper  to 
Lehi.  Another  notable  cliff  occurs  on  the  south  face  of  a  butte  east  of  Dove 
Creek,  and  is  visible  from  the  Central  Pacific  Railroad  between  Ombe  and 
Matlin.  The  eroded  material  was  in  this  case  swept  eastward  and  north- 
ward, being  carried  about  the  angle  of  the  butte,  then  an  island,  and  dis- 
tributed in  embankments  on  its  eastern  face. 

The  cut-terraces  of  the  Bonneville  shore  are  narrow  as  compared  with 
those  of  one  of  the  lower  shore-lines.  They  rarely  exceed  a  few  rods  in 
width.  A  good  example  can  be  found  on  the  flank  of  the  Wasatch  Range 
just  north  of  Big  Cottonwood  Canyon  and  others  on  the  north  end  of  the 
Oquirrh  Range  near  Black  Rock.  These  are  mentioned  as  being  easy  of 
access,  but  they  are  less  striking  than  some  that  are  carved  on  islands  at 
various  points  nenr  the  margin  of  the  Great  Salt  Lake  Desert. 


108 


LAKE  BONXEVJLLE. 


Spits  are  exceedingly  nnmermis,  being  attached  to  nearly  ;ill  (if  the 
ancient  islands  and  to  many  of  tln^  salients  of  the  main  coast.  <  )f  tliose 
having  some  magnitude,  the  most  accessible  are  at  Stockton  (1*1.  IX),  near 
Grantsville,  Tooele  Valley  (PI.  XV),  at  the  Point  of  the  Mountain  between 
Draper  and  Lehi,  on  Kelton  Butte  near  Ombe  station,  and  on  the  extremi- 
ties of  the  Terrace  Mountains. 


Fig.  22.— Butt*  near  Kelton,  Utali. 


Embankments  connecting  islands  with  each  other  (u-  with  the  main- 
land are  to  be  seen  at  the  west  end  of  Park  Valley,  at  Smithfield  in 
Cache  Valley,  on  Antelope  Island  in  Great  Salt  Lake,  a  few  miles  east  of 
George's  Ranch  south  oi  Deseret,  and  at  the  eastern  base  of  the  Gosiute 
Range. 

V-shaped  embankments  are  most  numerous  in  Snake  Vallo}-,  where  no 
less  than  ten  occur.  Four  are  attached  to  tlie  Simpson  Mountains  opposite 
to  the  Old  River  Bed  and  others  were  seen  in  Preuss  Valley  and  in  Beaver 
Creek  Valley. 


THE  CUP  UF  CUP  BUTTE.  109 

Typical  deltas  are  rare.  Certain  parts  of  the  valleys  of  all  the  }}riiici- 
pal  streams  were  occupied  by  inlets  or  estuaries,  and  the  heads  of  these 
inlets  received  alluvial  deposits  of  the  nature  of  deltas;  but  the  process  of 
accumulation  appears  usually  to  have  been  arrested  before  the  deposit  had 
extended  to  the  open  lake ;  and  afterward,  when  the  lake  receded  and  the 
streams  resumed  their  work  of  excavation,  all  but  scattered  patches  of  the 
alluvium  was  removed.  American  Fork,  Spanish  Fork,  and  Rock  Creek 
built  free  deltas  in  the  Utah  Bay,  and  Spring  Creek  furnished  one  to  the 
shore  of  Cedar  Bay,  but  these  v^ere  exceptional  and  small.  At  lower  levels 
great  deltas  were  constructed  by  many  streams,  and  the  deltas  of  the  Bonne- 
ville shore  ai'e  described  in  connection  with  these  in  one  of  the  later  sections 
of  this  chapter 

Plate  VI  exhibits  a  peculiar  circular  bar  observed  in  a  single  locality 
only.  The  sketch  is  in  part  ideal,  for  there  was  no  commanding  point  from 
which  to  obtain  the  bird's-eye  view  necessary  for  the  best  presentation  of  the 
subject.  Near  the  Old  River  Bed  there  is  a  group  of  quartzite  buttes  which 
were  surrounded  by  deep  water  and  formed  a  cluster  of  rocky  islands.  To 
the  north  and  northwest  the  deep  lake  stretched  unbroken  for  more  than 
one  hundred  miles,  but  in  all  other  directions  land  was  near  at  hand.  Each 
island  butte  shows  a  weather  side  facing  the  open  water  and  a  lee  side  fac- 
ing land.  Each  weather  side  is  marked  by  a  sea-cliff,  which  looks  down  on 
a  broad  terrace  carved  from  the  solid  rock.  The  lee  sides  have  no  cliffs, 
but  are  embellished  by  embankments  of  various  forms,  built  of  the  debris 
from  the  weather  sides.  In  the  case  of  the  butte  figured,  the  excavation  of 
the  platform  was  carried  so  far  that  only  a  small  remnant  of  the  original 
island  survived,  and  a  comparatively  small  additional  amount  of  wave  work 
would  have  sufficed  to  reduce  it  to  a  reef.  From  each  margin  of  the  sur- 
viving crest,  an  embankment  streams  to  the  leeward,  and  the  two  embank- 
ments, curving  toward  each  other,  unite  so  as  to  form  a  complete  oval.  At 
their  point  of  junction  they  are  a  few  feet  lower  than  where  they  leave  the 
butte.  Their  material  is  coarse,  ranging  up  to  a  diameter  of  two  feet,  and 
is  conspicuously  angular,  exhibiting  none  of  the  rounding  characteristic  of 
detritus  that  has  been  rolled  long  distances  upon  a  beach.  Within  the  oval 
rim  is  a  cup  38  feet  deep,  its  sides  and  lip  consisting,  on  the  north,  of  the 


no  LAKE  BONNEVILLE. 

rocky  slope  of  the  butte,  and  elsewhere  of  the  wall  of  loosely  heaped  blocks 
of  quartzite.  If  the  material  were  volcanic,  instead  of  sedimentary,  it  would 
be  easy  to  imagine  the  cavity  an  extinct  crater. 

Reservoir  Butte,  another  island  of  the  cluster,  is  figured  in  PI.  XXIV, 
and  further  represented  in  PI.  XXV  and  in  Fig.  3  of  PI.  VII.  It  derives 
its  name  from  a  series  of  natural  cups  analogous  to  the  one  just  described. 
These  are  attached  to  its  steep  slopes  at  various  levels,  the  process  of  con- 
struction having  been  repeated  at  as  many  epochs  in  the  history  of  the  oscil- 
lating lake.  In  this  connection,  only  the  cups  associated  with  the  highest 
shore-line  will  be  described.  The  longer  diameter  of  the  butte  trends  north 
and  south.  At  its  northern  extremity  and  along  its  northwestern  face  it 
displays  a  bold  sea-cliff,  from  50  to  100  feet  high,  springing  from  a  terrace 
at  the  Bonneville  level  several  hundred  feet  broad.  On  the  eastern  side  the 
cliff  and  terrace  give  place  near  the  north  end  to  a  massive  embankment, 
which  first  swings  free  from  the  side  of  the  butte  and  then  curves  inward 
toward  it,  meeting  it  somewhat  south  of  the  middle.  From  the  middle  of 
the  western  side  there  starts  a  similar  embankment,  which,  curving  through 
an  oval  arc  of  150°,  joins  the  butte  at  its  southern  extremity.  The  interval 
between  the  tei'mini  of  the  two  embankments,  a  space  of  1,000  feet  along 
the  southeastern  face  of  the  butte,  was  almost  unaffected  by  the  waves, 
being  neither  abraded  nor  covered  by  debris.  The  material  contained  in 
the  embankments  was  derived  exclusively  from  the  weather  side  of  the 
butte,  and  though  each  looped  embankment  joined  the  shore  at  two  points, 
the  conveyance  of  shore-drift  along  its  crest  appears  to  have  been  in  one 
direction  only.  It  is  difficult  clearly  to  realize  the  process  of  this  con- 
veyance, but  there  is  no  question  as  to  the  fact.  In  one  case  it  left  the 
shore  at  a  small  salient,  its  course  being  there  tangent  to  the  contour,  and, 
curving  through  an  arc  of  90°,  finally  assumed  a  course  directly  toward  the 
coast,  there  almost  precipitous.  In  the  other  case  it  left  the  shore  at  an 
obtuse  salient,  and  before  returning  swung  through  so  great  an  arc  as  nearly 
to  reverse  its  direction. 

The  cups  witliin  these  loops  have  been  somewhat  silted  u]i  in  modern 
times,  but  still,  except  for  their  diyness,  they  deserve  the  name  of  reser- 
voirs.    The  eastern  was  found  to  be  38  feet  deep.     The  embankments  were 


THE  GUPS  OF  RESEKVOIR  BUTTE.  HI 

built  in  deep  water  and  upon  a  foundation  inclining  steeply  from  the  shore. 
Their  forms  are  independent  of  the  configuration  of  their  foundation.  They 
were  not  accumulated  from  the  bottom  upward,  but  were  constructed  by 
successive  additions  at  the  end,  the  boulders  being  rolled  along  the  crest  of 
the  embankment  by  the  breakers  and  then  dropped  in  deep  water  at  its 
extremity.  The  outer  face  of  the  eastern  bar  has  a  height  above  its  base  of 
four  hundred  feet 

EMBANKMENT    SERIES. 

It  might  be  inferred  from  the  preceding  description  that  the  Bonneville 
shore-line  was  the  product  and  is  the  index  of  a  single  uniform  and  continu- 
ous water  stage.  Indeed,  it  has  been  so  regarded  by  every  observer  who 
has  published  an  account  of  it,  and  the  impression  is  readily  and  properly 
derived  from  its  ordinary  phase.  There  are,  however,  a  few  localities 
where  the  shore  mark  is  distinctly  resolvable,  and  shown  to  be  compounded 
of  several  similar  elements  at  slightly  different  heights  superposed  on  one 
another.  One  of  the  most  striking  localities,  and  at  the  same  time  the  one 
which  first  demonstrated  the  compound  nature  of  the  phenomenon,  is  repre- 
resented  in  PI.  X.  A  rocky  cape  projecting  from  the  east  shore  of  Snake 
Valley  sheltered  on  one  side  a  small  bay  opening  to  the  south.  Across 
this  bay  the  waves  built  a  series  of  bars,  as  represented  in  the  map.  The 
outermost  of  the  series,  that  is,  the  one  farthest  from  the  land,  is  connected 
at  its  eastern  end  with  a  shore  cliff  labeled  on  the  map  "  Bonneville  Sea- 
cliff";  and  this  cliff  runs  for  some  miles  southward  along  the  slope  of  the 
valley. 

A  study  of  the  locality  demonstrated  beyond  question  that  the  excava- 
tion occasioning  the  cliff  and  its  terrace,  furnished  the  material  for  the  bar, 
and  furthermore,  that  the  same  cliff  line  had  previously  been  connected 
with  each  bar  of  the  series. 

It  will  be  readily  understood  that  the  inner  bar  was  the  first  one  to  be 
built,  and  that  the  order  of  position  is  also  the  order  of  age.  They  stand  so 
nearly  at  the  same  level  that  no  one  of  them  could  have  been  formed  in  the 
rear  of  another.  Their  differences  of  level  therefore  record  changes  in  the 
relation  of  the  water  to  the  land  during  the  period  of  their  formation.     If 


112  LAKE  nONNEVILLE. 

we  call  the  inner  bar  No.  1  and  its  altitude  11  feet,  the  series  will  be  repre- 
sented by  the  following  list : 


Feet. 

No.  1 11 

No.  2 12 

No.  3 13 

No.  4 4^ 

No.  5 4i 


Feet. 
No.     6 ^ 

No.    7 8 

No.    8 0 

No.    •) 0 

No.  10 18 


No  importance  is  to  be  attached  to  the  individuality  of  the  bars.  There 
is  a  rhythm  of  action  in  the  process  of  their  formation  which  would  prevent 
the  construction  of  a  continuous  and  even-topped  terrace  under  the  most 
uniform  conditions.  If  the  bay  had  been  so  shallow  that  the  same  accu- 
mulation of  shore  drift  would  have  abridged  it  twice  as  much,  there  might 
have  been  twenty  bars  instead  of  ten.  The  first  tlu-ee  bars  signify  but  a 
single  epoch,  during  which  the  water  stood  at  one  level,  or  perhaps  rose 
slowly.  The  next  thi-ee,  which  in  point  of  fact  are  but  obscurely  indi\id- 
ualized,  represent  a  succeeding  water  stage  eight  feet  lower  and  ])ossibl\'  of 
somewhat  greater  dm-ation.  The  seventh  bar  shows  that  the  next  move- 
ment consisted  of  a  deepening  of  the  water  and  was  not  long  sustained. 
The  eighth  and  ninth  record  the  lowest  stage  of  all,  and  the  tenth  the  highest. 
The  tenth  contains  so  much  more  material  than  either  of  the  others,  being 
founded  in  deeper  water  and  carried  higher,  that  it  must  be  considered  as 
representing  a  longer  time,  and  may  be  coordinated  with  either  of  the  ante- 
cedent groups. 

Outside  the  tenth  bar  the  plain  slopes  gently  lakeward,  being  inter- 
rupted within  the  area  of  the  map  oidy  by  a  low  bar,  indicated  in  the  pro- 
file. This  bar  lies  so  far  below  the  others  that,  if  older,  it  might  not  have 
interfered  with  the  wave  action  necessary  to  their  formation.  Its  relati\e  age 
therefore  does  not  appear. 

The  process  of  construction  is  clearly  demonstrated  by  the  local  details. 
The  sea-cliff  was  excavated  from  the  alluvial  foot  slope  of  a  mountain  range. 
The  derived  material  consisted  primarily  of  boulders,  large  and  small,  sand, 
and  a  certain  portion  of  clay.  The  finer  part  was  immediately  washed 
lakeward  by  the  undertow.  That  of  middle  grade  was  carried  along  the 
shore  to  the  bay,  and  the  larger  boulders  remained  in  situ  until  sufficiently 


U  S. GEOLOGICAL    SURVEY 


LAKE  BOHNE'vTLLE      PL.X 


MAP   OF 

BAY  BARS  OF  THE   BON.XEVILLE    SHORE 

Near  \lw    Salt   Marsh,  in  Snake   Vallev,    Ttah 
Bv  ^^'   D  Johnson 


JO-ff'€t    Contours 


Y\%  Profile.  Vfjiical  Sralf  t/uef  times  the  Hofizontal . 


Julius  Bipti  4  Co.Iith 


DraifH  bu'G  Thoinpst 


SNAKE  VALLEY  BAY  BARS.  113 

reduced  by  attrition  to  be  transported.  In  the  bay  tlie  surface  currents 
^^ere  concentrated  by  converging  shores,  and  a  powerful  undertow  was  pro- 
duced, whereby  a  further  separation  was  effected,  the  shore  drift  being  de- 
prived of  a  coarser  grade  of  debris  than  that  previously  eliminated,  so  that 
tlie  matter  actxially  deposited  consisted  of  particles  ranging  from  a  lialf  inch 
to  turn-  inches  in  diameter, — a  clean  shingle  without  admixture  of  sand. 
The  sand  and  fine  gravel  thus  eliminated  by  the  undertow  were  deposited 
in  h)rge  part  near  the  liead  of  the  bay,  causing  the  water  to  shoal  rapidly, 
and  uhimately  determining  the  breaker  line  to  a  new  position  outside  the 
first,  and  tlius  initiating  the  construction  of  a  new  bar.  In  this  way  the 
depth  and  length  of  the  bay  were  at  the  same  time  progressively  diminished. 

For  purposes  of  comparison  the  profile  of  the  Snake  Valley  bars  has 
been  repeated  in  PI.  XI,  where  a  series  of  .similar  phenomena  are  also  drawn 
to  the  same  scale.     A  brief  description  will  be  given  of  each  locality. 

At  the  head  of  Skull  Vallev,  a  few  miles  north  of  Government  Creek, 
there  is  a  low  albnial  A\'ater-})arting  se})arating  the  valley  from  the  open 
desert  at  the  west.  At  the  time  of  the  Bonneville  water  stage  this  pass  was 
reduced  to  an  istlunus  only  a  few  rods  in  width,  and  the  Avater  was  shallow 
on  each  side.  On  the  Skull  Valley  side  there  were  formed  a  series  of  bay 
bars,  represented  in  profile  in  the  plate.  The  winds  under  the  influence  of 
which  they  were  formed,  covdd  have  blown  only  from  the  northward. 

The  third  profile  represents  in  similar  manner  a  group  of  bay  bars  ob- 
served a  few  miles  east  of  Sevier  Lake.  The  general  trend  of  the  old  shore- 
line is  there  north  and  south,  but  at  this  particular  spot  there  was  a  small 
cove  lying  on  the  north  side  of  a  rocky  promontory.  The  bars  were  formed 
by  northwesterly  winds. 

The  fourth  locality  is  a  few  miles  east  of  the  third,  l)eing  on  the  oppo- 
site side  of  the  Beaver  Creek  mountain  range  near  George's  Ranch.  A 
small  rocky  hill  was  insulated  at  high-water  stage  by  a  narrow  and  shallow 
strait,  and  across  this  strait  embankments  were  eventually  built  l)y  the  north- 
easterly winds.  The  first  of  the  embankments,  however,  did  not  completely 
close  the  passage,  and  remains  as  a  spit,  while  the  others  are  completed 
bars.     The  topographic  relations  are  shown  by  Fig.  23. 

MON  I 8 


114 


LAKE  BONNEVILLE. 


The  locality  of  tlie  fiftli  profile  is  the  southwestern  an<rle  of  Tooele  Val- 
ley, the  constructive  winds  hlmvin^-  in  this  case  also  fnun  the  northeast. 


.'5\v\ 


.■^. 


?3k 


§!,  "isi^-^^ 


Fig.  23. — Bars  near  George's  Ranch,  Utah. 


The  Dove  Creek  locality  is  far  to  the  uortli  of  the  others,  being  on  one 
of  the  ancient  islands  south  of  Park  Valley.  Trains  of  the  Central  Pacific 
Railway  pass  it  midway  between  Ombe  and  Matlin;  and  it  falls  within  the 
area  represented  by  PI.  XXII.  If  the  reader  will  turn  to  that  plate,  he  will 
see  that  the  Bonneville  shore  is  represented  on  the  southeastern  face  of  the 
island  by  a  sea-cliif  and  terrace,  and  on  the  northeastern  by  an  embankment. 
The  material  for  the  embankment  was  derived  from  the  sea-cliff  and  carried 
around  the  angle  by  shore  action,  doubtless  by  the  alternating  agency  of 
winds  from  diffei'ent  directions.  Below  the  Bonneville  embankment  there  is 
a  fine  series  of  other  embankments,  which  will  be  described  in  a  later  section 
of  this  chapter. 

The  surface  of  the  island  was  eroded  before  the  lake  epoch,  so  that  its 
slopes  consist  of  a  series  of  ridges  radiating  in  all  directions.  ( )n  the  south- 
east face  these  were  pared  away  at  the  Bonneville  level,  reducing  the  shore 
to  a  straight  cliff;  but  on  tlie  northeast  face,  where  the  action  of  the  waves 
was  constructive  instead  of  destructive,  the  ridges  retaiiied  their  form,  and 
the  embankment  was  built  across  from  one  to  another,  enclosing  a  series  of 
small  basins  occupied  by  lagoons.  The  first  and  second  of  these  basins  are 
now  about  twenty  feet  deep,  ;iud  are  undrained.     The  enclosing  parapet  is 


OTHER  EMBANKMENT  SERIES.  115 

a  simple  bar  not  susceptible  of  subdivision,  the  formative  currents  appear- 
ing to  have  held  a  uniform  course  during  its  construction.  Tlie  third  basin 
is  shallower,  and  a  recently-formed  drain  reveals  a  section  of  its  parapet, 
sliowing  it  to  consist  of  the  three  bars  indicated  in  the  lowest  profile  of  PI. 
XL  The  current  at  tliis  point  nuist  have  been  tln-o\\n  fartlier  and  farther 
from  tlie  land  as  accumulation'proceeded.  The  fourth  basin  is  similar  to  tlie 
third,  but  the  fifth  lias  no  inner  bar.  The  low-lying  inner  liars  are  obvi- 
ously elder  than  the  higli  outer  l:)ar,  and  all  the  minor  features  of  the  locality 
tend  to  the  conclusion  that,  during  the  period  of  their  formation,  the  train  of 
shore  drift  did  not  extend  to  the  fifth  basin.  It  is  inferred  by  analogy  that 
there  was  an  antecedent  time,  within  the  epoch  of  the  Bonneville  shore, 
when  the  shore  drift  failed  to  reach  the  thii'd  basin,  so  that  the  series  of  bars 
there  exhibted  is  incomplete. 

Let  us  now  consider  the  question  why  the  successively  formed  bars  in 
these  several  localities  differ  in  height.  At  least  three  general  answers  are 
possible.  The  embankments  were  l)uilt  upon  the  land  by  means  of  the 
water  of  the  lake,  thro-^^'n  into  motion  by  the  wind,  and  their  variations  in 
height  may  have  resulted  from  variations  of  the  wind  or  of  the  water  or  of 
the  land.  It  is  conceivable  that  the  highest  bars  were  produced  by  storms 
of  exceptional  force,  and  the  lower  by  less  violent  storms.  It  is  conceivable 
that  the  water  of  the  lake  rose  and  fell  from  time  to  time,  and  that  the  bars 
marked  successive  stages.  It  is  conceivable  that  the  land  rose  and  sank,  so 
as  to  bring  different  horizons  successively  within  reach  of  the  waves;  and 
finally,  it  is  conceivable  that  two  or  more  of  these  causes  conspired  to  pro- 
duce the  phenomena. 

A  movement  of  the  land  might  have  been  general,  involving  the  entire 
basin,  or  there  might  have  been  differential  movements,  changing  the  rela- 
tive height  at  various  points.  In  the  first  case  the  lake  would  be  carried 
up  and  down  with  its  basin,  and  there  would  be  no  change  in  the  relation 
of  shore  and  water.  The  oidy  land  movement  therefore  which  could  pro- 
duce the  phenomena,  is  one  of  a  differential  nature,  and  this  would  of  neces- 
sity give  rise  to  dissimilar  results  at  widely  separated  places.  If  the  sev- 
eral bar  series  are  harmonious  in  their  vertical  relations,  it  is  safe  to  say 
that  they  do  not  indicate  oscillations  of  land. 


116  LAKE  BONNKVILLB. 

A  movement  of  the  water  surface  would  evidently  produce  clian<i-cs  of 
the  same  vertical  amount  at  every  point,  so  that  the  hypothesis  of  lake  os- 
cillation would  be  negatived  if  the  several  systems  of  ditterentiated  bars 
were  found  to  be  inharmonious. 

The  remaining  hypothesis  of  imequal  storm  force  may  take  two  foi-ms. 
In  the  first  place,  it  might  be  imagined  that  each  indi\ndual  embankment  of 
exceptional  height  was  the  creature  of  a  single  storm,  or  of  a  limited  series 
of  storms ;  or,  in  the  second  place,  it  is  conceivable  that  the  general  char- 
acter of  the  weather  underwent  secular  variations  ;  so  that  from  century  t(j 
century  there  were  notable  changes  in  the  maximum  force  of  storm  winds. 
Under  the  first  view,  Ave  should  anticipate  that  localities  dominated  by 
Avinds  from  different  directions  Avould  not  accord  in  the  character  of  their 
bar  systems;  the  approximate  coincidence  of  exceptional  storms  from  oppo- 
site directions,  being  only  adA^entitious,  could  not  be  expected  to  recin-  with 
uniformity.  Under  the  second  A-icAv,  on  the  contrary,  there  Avould  be  uni- 
foiTtiitA'  of  result, — a  general  change  of  climate  affecting  all  localities  alike. 
The  eolian  hypothesis  Avould  therefore  be  disproved  neither  liy  the  har- 
mony nor  by  the  lack  of  harmony  of  the  obserA'ed  results.  It  admits, 
hoAvever,  of  an  independent  test  of  crucial  vahie.  Great  AvaA-es  are  unques- 
tionably able  to  transfer  coarser  shore  drift  than  small  Avaves,  so  that  Avhere 
the  supply  of  debris  is  heterogeneous,  the  character  of  that  selected  for  the 
construction  of  embankments  is  an  index  of  the  poAver  of  the  AvaA^es.  If, 
therefore,  in  localities  Avhere  the  shore  drift  is  derived  from  the  luisorted 
allnvium,  it  be  found  that  the  higher  bars  contain  coarser  fragments  than  the 
lower,  it  is  i)roper  to  infer  that  they  oAve  their  superior  height  to  superiority 
of  Avave  force;  l)iit  if  it  be  found  that  all  the  bars  of  a  series  are  uniform  in 
composition,  their  inequalities  of  size  cannot  be  referred  to  variations  of 
storm  force,  either  local  or  general. 

As  a  matter  of  fact,  there  is  no  correlation  of  coarse  material  Avitli  high 
bars.  The  Snake  Valley  series  Avas  scrutinized  Avitli  reference  to  this  point 
and  found  to  be  uniform  in  conq)osition.  We  may  then  cease  to  consider 
the  Avind,  at  least  so  far  as  the  more  iinjiortaht  A-ariations  are  concerned,  and 
limit  attention  to  the  hypotheses  ot  land  nioxcmcnt  and  lake  iiio\ cineiit. 
The  theory  of  laud  moA-ement  Avould  be  sustaineil  1>\'  a  discordanci'  among 


I :,  s,  (;i':iii.oi:li..\l.  suiA'KY 


REPOHT  Oyr  LAKE  BONNEVlLIjE.  J 'J, ATE XI 


HYPOTHESES  AND  TESTS.  1 1 7 

the  systems  of  bars.  The  theory  of  lake  movement  would  be  sustained  by 
an  accordance.  An  imperfect  accordance  miglit  indicate  a  combination  of 
the  land  and  lake  changes. 

The  facts  are  assembled  in  PI.  XI,  to  which  the  reader  is  again  referred. 
Each  of  the  profiles  represents  a  section  at  right  angles  to  the  system  of 
bars  it  illustrates,  and  all  are  dra\\u  to  the  same  scale,  the  vertical  element 
being  exaggerated  three-fold.  They  are  grouped  on  the  page  in  such  man- 
ner that  the  outer  embankments  of  the  several  series  appear  at  the  right  and 
fall  in  the  same  vertical  column. 

The  first  consideration  affecting  the  comparison  is  that  each  series  pre- 
sumably represents  the  same  period  of  time,  so  that,  if  a  correlation  is  pos- 
sible, the  embankment  drawn  at  the  right  in  one  series  should  correspond 
to  that  at  the  right  in  the  others.  That  at  the  extreme  left  in  one  should 
correspond  to  that  at  the  extreme  left  in  tne  others,  and  the  intermediate 
portions  should  be  comparable.  The  only  exception  to  that  rule  is  in  the 
case  of  the  Dove  Creek  series,  which,  as  already  explained,  may  represent 
only  the  later  portion  of  the  time  consumed  in  the  formation  of  the  others. 

Restricting  attention  to  the  first  five  groups  of  bars,  we  note  first  that 
the  right-hand  member  of  each  is  higher  than  any  other.  The  second  con- 
spicuous fact  is  that  the  member  second  in  size  stands  at  the  extreme  left. 
To  this  there  is  a  single  unimportant  exception,  which  vanishes  if  we  con- 
sider the  three  bars  at  the  left  of  the  upper  profile  to  constitute  a  single 
member  comparable  with  the  individual  bars  of  the  other  series.  It  is  by 
no  means  improbable  that  a  more  careful  stud}'  of  the  Skull  Valley  locality 
would  resolve  the  left-hand  maximum  into  such  a  series  as  was  found  in 
Snake  Valley. 

The  most  extended  series  exhibits  a  third  maximum,  lower  than  either 
of  the  others,  but  intermediate  in  position  and  standing  somewhat  to  the 
right  of  the  middle  of  the  profile.  No  other  profile  shows  a  third  maximum, 
but  three  of  them  exhibit  bars  of  approximately  the  same  height,  which  may 
be  conceived  to  represent  it,  if  the  bars  of  the  second  minimum  are  assumed 
to  have  been  covered  and  concealed  by  the  great  outer  bar.  It  is  easy  to 
understand  that  a  condensed  or  foreshortened  series  would  exhibit  super- 
ficially only  the  maxima  of  a  fully  extended  series.     It  therefore  seems 


118  LAKE  BONNEVILLE. 

proper  to  correlate  the  intermediate  maximum  of  the  upper  profile  with  the 
bar  appearing  at  the  inner  base  of  the  outer  niaxiiiuiin  in  tlie  second,  tliinl, 
and  foui'th  profiles.  In  the  fiftli  profile,  bars  representing  tlie  fii-st  mi  id  third 
maxima  stand  in  juxtaposition;  and  it  is  necessary  to  assume  tluit  tlic  inter- 
vening maximum,  as  well  as  the  two  minima,  is  covered  and  concealed. 

It  thus  appears  that,  in  their  most  general  features,  the  groups  of  bars 
are  in  accordance,  with  no  greater  variation  than  might  readily  be  ascriljed 
to  local  disparity  of  condition. 

The  difference  between  the  altitude  of  the  outer  bar  and  that  of  the 
intermediate  maximum  was  measured  in  tour  localities.  In  Snake  Valley 
it  is  10  feet,  in  Skull  Valley  12  feet,  in  Sevier  Lake  Valley  15.3  feet,  and 
at  George's  Ranch  15  feet.  The  range  of  these  measurements  is  5  feet,  and 
this  must  be  regarded  as  a  real  discrej^ancy,  though  not  a  gi-eat  one. 

The  altitude  of  the  outer  bar  above  the  inner  maximum  was  measured 
at  five  points  and  found  to  be  5  feet,  10  feet,  10  feet,  7  feet,  8  feet, — the 
enumeration  following  the  order  of  the  diagrams.  Here  again  the  range 
is  5  feet. 

If  the  inner  bar  be  compared  with  the  intermediate  maximum  instead 
of  with  the  outer  bar,  the  diff"erences  are  found  to  be  5  ft,  2.7  ft.,  5.3  ft.,  and 
8  ft.,  showing  again  a  range  of  5  feet. 

Finally,  the  low  bars  observed  between  the  inner  and  intermediate 
maxima  have  approximately  the  same  relation  in  tlie  tln-ee  localities  where 
they  were  observed.  Compared  witli  the  intermediate  maximum,  their 
measured  difi"erences  ai'e  3.5  ft,  2.3  ft.  and  4.7  ft.,  tlie  nuige  being  2^  ft. 

These  com])arisons  exhaust  the  data,  and  they  appear  to  establish  the 
systematic  hannony  of  the  phenomena.  It  is  inconceivable  that  such  ac- 
cord shoidd  be  fortuitous.  The  most  complete  record  (that  in  which  the 
bar  system  was  spread  out  most  broadly,  so  as  to  resolve  it  most  completely 
into  its  elements)  exhibits  three  maxima  with  intermediiitc  miiiim;i.  Tlie 
record  second  in  extent  shows  the  three  maxima  and  one  miniiiimii, — the 
other  minimum  being  overplaced  and  concciilcd.  Tlie  Sevier  Lake  ri'cord 
shows  the  same  four  elements,  but  more  compactly  arranged.  At  George's 
Ranch  the  three  maxima  are  so  closely  crowded  that  l)oth  minima  are  con- 
cealed.    At  the  head  of  Tooele  Vallev,  the  outer  and  inner  maxima  are  in 


ADJUSTMENT  BY  LEAST  SQUARES.  119 

juxtaposition  and  all  the  intermediate  elements  ot"  the  series  are  buried. 
The  ordinary  bay  bar,  in  which  all  the  elements  are  welded  together  and 
covered  by  the  last  and  highest  deposit,  is  logically  the  final  term  of  the 
series  of  facts. 

The  hypothesis  of  water  movement  is  therefore  sustained.  The  chang- 
ing relations  of  land  and  water  during  the  formation  of  that  complex  record 
to  which  we  have  applied  the  title  of  the  Bonneville  shore-line,  were  brought 
about  by  the  alternate  rising  and  falling  of  the  water  surface.  While  the 
higher  bars  were  being  formed,  there  was  more  water  in  the  basin;  while  the 
lower,  less. 

Having  thus  established  the  correlation  of  the  series  of  profiles  by  a 
comparison  of  the  unmodified  facts  of  observation,  it  is  now  proper  to  adjust 
them  to  one  another  for  the  purpose  of  ascertaining  the  mean  (juantitative 
value  of  changes  of  water  level.  Applying  the  method  of  least  squares,  we 
obtain  for  the  most  probable  values  of  the  water  stages,  referred  to  the  low- 
est of  the  series  as  zero  and  arranged  in  the  order  of  time:* 

feet. 

First  maximum 12.3  ±  .2 

First  minimuin 3.0  ±  .2 

Second  m.axiinum   7,3  i  .2 

Second  minininm 0.0 

Third  maximum 20.1  ±  .2 

Adjusted  to  the  same  zero,  the  observations  at  the  several  localities  ex- 
hibit the  following  relations: 

Table  II.     Embankment  Series  of  the  Boiinei^Ule  Shore-line. 


Locality. 

Allilnile  in  feet. 

Variation  fioDi  ailjusfoil  mean. 

1st 
Max. 

1st 
Miu. 

2.1 
Max. 

2a 

Min. 

3ll 
Mas. 

lat 
Max 

Iflt 
Min 

2il 
Max 

2.1 

Mm 

ad 
Max 

Snake  V.illey 

Skull  Valley 

Sevier  Lake  Valley. 

George's  Ranch 

Tooele  Valley 

in.o 

10.  .■! 
12  2 
13.0 
12.2 

4.5 
5.3 
2.  2 

8  0 
7.6 
C.9 
5.fi 

0.0 


18.0 
20.3 
22.  2 
20.6 
20.2 

+  .7 
—2.0 

—  .1 

+  1.3 

—  .1 

+  .6 
+  1.4 
-1.7 

+  .7 
+   .3 
—  .4 
-1.7 



—2.1 
+  .2 
+  2.1 
+  .5 

+  •1 
1 

'  The  computation  incliuled  data  from  the  Dove  Creek  protile  aud  from  tho  PruiiiiB  Valley  bars. 
It  was  performed  by  Mr.  A.  L.  Webster. 


120  LAKE  BONNEVILLE. 

The  residual  discordance,  as  shown  by  the  cohimns  at  the  nght,  is  not 
large,  thougli  it  is  somewhat  greater  than  the  range  ot"  variation  found  in  the 
longitudinal  profile  of  the  crest  of  a  single  har.  A  part  of  it  is  i)n)b;il)lv  due 
to  inaccuracies  of  measurement;  no  instrinnents  of  j)recision  were  emj)loyed, 
and  the  methods  at  more  than  one  locality  were  improvised  and  crude.  There 
will  be  no  impro})riety  in  referring  the  remainhig  part  to  exceptional  storms 
combined  with  local  conditions. 

Reverting  now  to  the  Dove  Creek  series,  wliicli  the  field  observations 
gave  reason  to  suspect  of  incomj)leteness,  we  find  by  inspection  that  its  two 
levels  can  readily  be  correlated  with  the  second  and  third  maxima  of  the  gen- 
eralized profile.  It  is  highly  probable,  therefore,  that  the  earlier  water 
stages,  including  the  first  maximum  and  the  first  minimum,  failed  to  make 
an  independent  record  at  that  ])lace. 

To  convert  the  data  fully  into  terms  of  lake  history  it  is  necessary  to 
comjiare  the  epochs  of  formation  of  the  several  l:)ars  in  the  matter  of 
duration  as  well  as  in  that  of  water  stage.  The  amount  of  shore  di'ift 
accumulated  in  the  several  bars  has  to  be  considered,  and  likewise  the 
manner  in  which  the  varying  water  stage  affected  the  rate  of  accunudation. 
A  determination  of  absolute  duration  is  manifestly  out  of  the  (piestion, 
and  any  estimate  of  relative  duration  is  largely  a  matter  of  indi\ddual  judg- 
ment. 

An  attempt  has  been  made  in  Fig.  G  of  PI.  XI  to  represent  the  oscilla- 
tions and  their  periods  in  a  quantitative  way,  so  far  as  they  are  dediu-ible 
from  the  plienomena.  If  the  facts  permitted  xis  to  draw  the  full  curve  of 
oscillation  with  all  its  details  it  would  unquestionably  be  far  less  simple. 
The  number  of  minima  concealed  by  the  bars  of  even  the  most  extended 
series  may  be  very  great;  and  it  is  even  possible  that  these  bars  do  not  re})- 
resent  a  continuous  history.  If,  after  the  series  had  been  ])artly  formed,  the 
lake  shrank  to  nuich  smaller  dimensions,  returning  to  the  region  of  the  Bon- 
neville shore  only  after  a  long  interval,  there  seems  no  wav  to  determine 
this  fact  by  the  phenomena  of  tlie  shore.  Probablv  tlie  only  conclusions 
deducible  from  the  profiles  are;  first,  that,  when  the  lake  basin  was  full,  the 
position  of  the  water  level  was  unstable;  and,  second,  that  of  a  series  of 
high-water  stages,  the  latest  was  the  highest  of  all. 


INTERPRETATION  OP  V-HARS.  121 

It  will  perhaps  occur  to  the  reader  that  the  enumeration  and  discussion 
of  these  facts  have  been  needlessly  prolix;  and  this  I  am  not  prepared  to 
deny.  But  it  may  be  said  in  extenuation  that  the  phenomena  belong;-  to  a 
novel  tvpe,  and  that  the  method  of  investigation  Avas  so  far  new  that  the 
simple  conclusions  finally  reached  required  for  their  establishment  a  full 
presentation  of  the  alternative  hyj^otheses  eliminated  by  the  investigation. 
In  the  sequel  it  will  appear  that  even  these  simple  conclusions  afford  a  key 
to  the  understanding  of  some  of  the  most  important  elements  in  the  history 
of  the  lake,  and  through  that  history  are  brought  into  relation  to  the  prob- 
lem oi'  the  physical  condition  of  the  earth's  interior. 

One  result  of  tlie  discovery  and  interpretation  of  the  groups  of  bay 
bars  of  the  Bonneville  shore-line  was  the  explanation  of  certain  features  of 
the  V-embankments  which  had  previously  been  problematic.  V-embank- 
ments  have  already  been  described  as  triangular  terraces  built  against  mount- 
ain slopes  at  the  shore  level,  and  margined  toward  the  lake  by  even-topped 
parapets.  In  the  light  of  the  conclusions  thus  detailed  it  becomes  evident 
that  this  conformation  was  occasioned  by  oscillations  of  the  lake  during  the 
period  of  the  formation  of  the  terrace.  The  space  within  the  parapet  is 
usually  occupied  by  a  playa,  the  surface  of  which  is  from  five  to  eight  feet 
below  the  enclosing  rim.  This  represents  a  certain  amount  of  silting  up  of 
the  basin.  If  there  were  no  filling,  it  cannot  be  doubted  that  the  interior 
of  each  enclosure  would  exhibit  a  series  of  bars  parallel  to  one  or  both  arms 
of  the  jiarapet,  and  corresponding  in  height  and  arrangement  to  the  bay  bars. 
In  fact,  this  very  phenomenon  was  finally  observed  at  several  localities. 
The  most  interesting  are  in  Preuss  Valley  along  the  western  base  of  the 
Frisco  Mountains.  In  that  valle}'  the  shore  features  of  many  different  hor- 
izons afforded  an  instructive  study,  and  were  carefully  mapped.  PI.  VIII 
gives  a  general  view  of  the  phenomena  on  the  east  side  of  the  valley,  and 
it  will  be  noted  that  the  Bonneville  shore-line  includes  three  of  these  tri- 
angular terraces.  The  same  appear  on  a  somewhat  larger  scale  in  Pis. 
XVI,  XVII,  and  XVIII.  The  parapet  associated  with  the  middle  group  of 
embankments  (PI.  XVII)  offers  an  exception  to  the  general  rule,  in  that  it 
is  broken  through  by  the  drainage,  so  that  the  interior  contains  no  playa. 
It  contains  instead  the  eroded  remnants  of  a  system  of  bars  parallel  to  the 


122  LAKE  BONNEVILLE. 

southern  pai-apet.  In  this  system  it  is  easy  to  recognize  the  equivalents  of 
first  and  second  maxima  of  the  Snake  Valley  bars,  holding  their  j^roper  re- 
lation to  the  para])et,  which  corresponds  to  the  third  or  outer  maximum. 
The  V-enibankment  of  the  south  group,  PI.  XVIII,  is  undi-ained,  but  its 
filling  has  not  progressed  so  far  as  to  obliterate  the  inner  maximum.  Two 
elements  of  the  bay-bar  series  are  therefore  represented ;  and  the  same  were 
found  in  the  north  group  of  embankments. 

In  the  case  of  the  middle  and  southern  of  these  Preuss  Valley  embank- 
ments, and  in  two  f)r  three  other  instances,  the  interior  embankments  are 
parallel  to  one  parapet  only,  so  as  to  constitute  with  that  a  series  of  parallel 
ridges  connecting  the  remaining  parapet  with  the  shore.  It  seems  evident 
that  in  these  cases  the  growth  of  the  triangular  terrace  was  chiefly  or  en- 
tirely by  additions  to  a  single  face;  and  it  may  not  be  improper  to  define 
the  aggregate  structure  as  a  spit  gradually  projected  into  the  lake  by  recur- 
rent storms  from  a  certain  direction  and  buttressed  by  successively  formed 
bay  bars  connecting  its  extremity  at  various  stages  with  other  points  of  the 
shore,  the  bay  bars  being  the  work  of  a  series  of  storms  from  a  diff'erenr 
direction. 

The  variety  of  contour  assumed  by  the  parapets  of  the  V-erabank- 
ments,  and  by  the  crests  of  the  hooks  and  loops  with  which  they  are  more 
or  less  affiliated,  is  illustrated  by  PI.  VII. 

DETERMINATION   OF  STILL  WATER  LEVEL. 

One  of  the  collateral  results  of  the  composite  nature  of  the  Bonne- 
ville shore-line  is  a  discrepancy  in  the  evidence  aft'orded  by  different  parts 
of  the  shore  phenomena  as  to  tlie  altitude  of  the  ancient  water  level.  Tliose 
parts  of  the  coast  which  were  given  their  character  by  excavation  indicate 
the  water  level  by  a  line  forming  the  angle  between  a  cliff  above  and  a  ter- 
race below,  and  this  line  often  represents  the  lowest  of  the  series  of  water 
levels  recorded  by  the  bay  bars.  Tlie  im])ression  made  by  the  waves  at  the 
last  and  highest  level  is  usually,  thougli  not  always,  so  faint  that  it  has  been 
obliterated  by  the  falling  down  of  the  cliff.  On  the  other  hand,  those  parts 
of  the  shore  formed  by  the  accunuilation  of  detritus  appear  as  a  rule  at  the 
highest  water  stage  only.     The  localities  in  which  embankments  represent- 


U  S.GEOLOGIC^AL    S'JRlrEy 


JjAI-'vE   BOiJN'B'.lr.bE      PL.  xn 


42°'- 


41' 


40' 


39° 


38° 


US' 


!uliu9  Bien  *  Co,  lilK 


MAP  OF 

E  BONNEVILLE 

I'lIKSKNT  UYliRdllRAFMIC  DIVISIONS 

OF     THE 

BONXE\TLLE   BASIN 

n  red ) 
and 

The  areas  with  alUUide 
ijreater  than  7000  feet. 

cin  "blice ; 
\'n[c  The  dotted  lines  indicate  dottbi 


42 


41° 


SCA  LE  :     t 


Dt;i«Ti  tfv  C  Thuiopsi 


FINDING  TUE  STILL  WATER  LEVEL.  123 

ing  progressive  action  are  differentiated,  are  exceptional ;  and  in  ordinary- 
cases  the  latest  additional  material  covers  all  the  preceding.  For  an  accu- 
rate determination  of  the  height  of  the  niaxiinnni  water  level,  it  is  therefore 
necessary  to  consider  the  character  of  the  record  to  which  measurement  is 
aj)plied.  The  base  of  a  sea-cliff  is  apt  to  give  too  low  an  indication,  while 
the  crest  line  of  an  embankment  is  not. 

If  this  element  were  the  only  one  to  'be  taken  into  accoimt,  it  would  be 
a  simple  matter  to  ascertain  in  every  region,  by  using  emljankments  only, 
the  precise  height  of  the  old  water  level;  but  there  is  unfortunately  a  com- 
plication. The  crest  of  a  completed  embankment  always  stands  somewhat 
higher  than  the  still  water  level  of  the  lake  to  which  it  pertains ;  and  the 
amount  of  the  difference  depends  on  conditions  which  are  not  entirely  sim- 
ple. They  include  some  elements  of  the  configuration  of  the  bottom,  and 
especially  the  magnitude  of  the  largest  incident  waves.  The  same  elements 
of  configuration  affect  also  the  record  embodied  in  the  base  line  of  a  cliff, 
but  the  magnitude  of  the  waves  does  not.  On  a  coast  foeing  deep  water 
the  base  of  the  sea-cliffs  coincides  very  closely  with  the  still  water  level. 
If,  therefore,  the  surface  of  Lake  Bonneville  had  not  fluctuated  while  near 
its  highest  stage,  the  sea-clifis  would  aft'ord  a  more  intelligible  record  of  its 
precise  horizon  than  the  embankments. 

As  the  case  stands,  the  best  indications  are  sometimes  afforded  by  one 
class  of  facts  and  sometimes  by  the  other.  Wherever  it  is  evident  that  the 
sea-cliffs  associated  \\  ith  the  maxinuun  water  stage  survive,  their  base  is 
assumed  to  give  the  most  authentic  record.  Where  these  cannot  be  dis- 
criminated, embankments  have  been  em])loyed,  an  allowance  being  made 
for  their  height  above  the  water  line.  This  allowance  is  a  matter  of  judg- 
ment in  each  individual  case. 

It  will  be  instructive  to  illustrate  the  difficulties  of  the  subject  by  a  few 
examples. 

If  the  reader  will  refer  to  the  general  map  of  the  lake,  he  will  see  that 
the  Jordan  valley  was  occupied  ]>y  a  large  bay  receiving  waves  from  the 
open  lake,  while  the  Utah  Lake  valley  was  occupied  by  a  land-locked  bay 
affected  by  no  waves  but  those  generated  within  its  own  borders.  These 
two  bays  were  joined  by  a  narrow  strait  at  the  locality  now  known  as  the 


124  LAKE  BONNEVILLE. 

Point  of  the  Mountain,  and  from  the  coast  east  of  tliis  strait  tliere  was  con- 
structed an  iniiiiense  triaiij^'uhir  terrace,  receiving  upon  one  side  the  (h'tritus 
rolled  by  the  great  waves  of  the  Jordan  Bay,  and  on  the  other  the  slioic  drift 
moved  by  the  snitdler  waves  of  the  inner  bay. 

The  parapets  on  the  two  margins  of  the  V-shaped  embankment  give 
clear  expression  to  this  disparity  of  conditions.  Tliat  facing  Jordan  Bay  is 
the  more  massive  and  tlie  longer,  and  the  other  is  Iniilt  against  it  as  a  sort 
of  appendage.  The  general  altitude  of  the  larger  bar  is  six  feet  greater  than 
that  of  the  less;  and  since  the  latter  has  all  the  features  of  a  completed  endjank- 
raent  rising  above  the  water  level,  it  follows  that  the  northern  or  higher  eni- 
bankiuent  was  built  more  tlian  six  feet  above  the  still  water  level  of  the  lake. 

Kelton  Butte  (Fig.  22)  projected  its  apex  as  a  small  island  above  the 
water  level  and  was  surrounded  by  deep  water.  From  one  direction  it  re- 
ceived waves  propagated  through  a  distance  of  thirty  miles,  and  by  these  a 
cliff  and  terrace  were  carved  out  and  an  embankment  was  constructed.  The 
terrace  is  itself  tei-raced  in  such  way  as  to  encoiu-age  the  belief  that  the  base 
of  the  cliff  corresponds  Avith  the  highest  water  stage;  but  this  base  is  7i  feet 
lower  than  the  contiguous  embankment. 

At  a  locality  in  Preuss  Valley,  where  the  conditions  did  not  admit  of 
the  generation  of  waves  of  great  size,  an  embankment  has  lieen  connected 
by  leveling  with  a  sea-cliff  and  terrace,  and  found  to  be  5  feet  higher  than 
the  terrace.  In  this  case  part  of  the  discrepancy  is  doubtless  referable  to 
the  failure  of  the  waves  at  the  highest  stage  to  score  a  durable  record  on 
the  face  of  the  sea-cliff"  carved  at  a  lower  level. 

A  similar  measurement  was  made  at  Wellsville  in  Cache  Valley,  where 
also  the  waves  were  not  of  the  greatest  magnitude,  and  gave  a  difference  of 
19  feet.  At  the  opposite  end  of  Cache  Valley,  near  the  town  of  Franklin, 
tliere  is  a  small  indentation  in  the  shore  in  which  an  isolated  embankment 
has  been  preserved  with  a  crest  12  feet  above  the  base  of  the  adjacent  sea- 
cliff;  and  in  a  sheltered  spot  north  of  the  town  of  Tecoma,  in  the  northwest- 
ern portion  of  the  Ijasin,  the  measurement  of  similar  details  showed  a  differ- 
ence of  20  feet. 

The  state  of  preservation  of  the  embankments  is  all  that  could  be  de- 
sired for  purposes  of  measurement.     The  innjority  of  them  are  composed  of 


DEPTH  OF  THE  OLD  LAKE.  125 

gravel,  and  are  exempted  by  their  ridge-like  form  from  the  destructive  action 
of  cross-flowing  drainage.  A  few  inches  at  most  would  express  the  loss  their 
crests  have  sustained  from  the  wash  of  the  rain.  With  tlie  sea-cliffs  and 
wave-cut  terraces  it  is  different.  The  decay  of  a  cliff'  throws  (lo\\n  a  con- 
stantly increasing  amount  of  del)ris,  which  falls  to  the  base  ;ui(l  foi-ins  a 
talus;  and  every  little  drainage  channel  by  which  a  cliff' is  divided  spreads-a 
heap  of  alluvium  upon  the  terrace  below.  The  base  of  the  cliff,  therefore — 
the  element  of  the  jirofile  which  for  purposes  of  measurement  it  is  most 
desiral:)le  to  recognize — has  been  almost  universally  covered  by  the  rising 
alluvium,  so  that  its  precise  position  is  a  matter  of  estimation  or  indirect 
observation. 

The  discovery  that  the  old  Avater  line  is  no  longer  of  uniform  height, 
and  the  tact  that  its  variations  of  altitude  afford  a  means  of  measuring  the 
recent  differential  movements  of  the  earth's  crust  within  the  basin,  give  occa- 
sion for  great  regret  that  the  exact  identification  of  the  highest  water  stage 
is  so  difficult  a  matter.  In  a  majority  of  instances  the  range  of  uncertainty, 
after  all  allowances  have  been  made,  amounts  to  five  or  six  feet. 

DEPTH. 

The  greatest  depth  of  the  lake  was  about  1,050  feet;  and  this  depth 
obtained  over  all  the  western  ])art  of  the  present  site  of  Great  Salt  Lake. 
The  })oint  west  of  Antelope  Island,  where  the  deepest  water  in  Great  Salt 
Lake  is  now  found,  did  not  sustain  the  same  relation  to  Lake  Bonneville, 
))ut  was  rivaled  and  perhaps  sur})assed  l)y  jioints  between  Promontory 
and  the  Terrace  mountains.  The  Great  Salt  Lake  Desert  has  now  a  re- 
markably flat  floor,  and  the  ancient  de])th  of  water  above  it  did  not  vary 
greatly  in  diflerent  parts.  The  mean  de])th  of  the  main  body  of  L'lke  Bon- 
neville was  in  the  neighborhood  of  800  feet.  The  Sevier  body  had  a  max- 
imum depth  of  G50  feet,  and  Esciilante  bay  of  about  UO  feet. 

THE  MAP. 

The  mapping  of  the  Bonneville  shore  received  careful  attention;  audit 
is  pro])alde  that  the  extent  and  fonn  of  no  modern  lake  in  an  unsettled 
country  is  more  accurately  known.     The  determination  of  certain  questions 


126  LAKE  BONNEVILLK. 

with  reference  to  overflow  necessituted  tlie  inspection  (if  a  lariic  part  of  the 
periphery;  and  the  knowledge  thus  obtained  ol'  tlic  position  of  tlic  coast  was 
afterwards  systematically  supplemented  until  a  complete  ma])  Wecame  possi- 
ble. T\u'  insulai-  mountains  standing-  on  Oreat  Salt  Lake  Desert  were  not 
visited,  and  the  coast  lines  about  their  sides  were  for  the  most  part  deduced 
from  the  contours  of  the  published  maps  of  the  Survey  of  the  Fortieth 
Parallel;  but  with  this  exception  all  of  the  coast  was  seen  by  some  member 
of  the  corps  and  sketched  from  actual  observation.  A  large  pai-t  of  it  was 
examined  by  more  than  one  individual.  The  map  is  indebted  to  Mr.  C4il- 
bert  Thompson  for  tlu^  details  of  the  west  coast  between  Deep  ('reek  and 
Montello,  and  for  the  bays  at  the  north  ends  of  Pocatello  and  Malade  \'al- 
leys.  He  delineated  also  the  details  west  of  Sevier  Lake  and  in  the  southern 
extension  of  White  Valley.  The  map  is  indebted  to  j\Ir.  Thompson  and  Mr. 
Albert  L.  Webster  for  the  outlines  of  the  Escalante  Bay.  Mr.  Willard  I). 
Johnson  delineated  the  shores  of  the  White  Valley  Bay  and  the  coasts  on 
the  Dugway,  MacDowell,  and  Simpson  Mountains.  The  outline  in  Tintic 
Valley  was  furnished  by  Mr.  H.  A.  Wheeler.  Mr.  Israel  C.  Russell  map])ed 
the  bay  east  of  the  Canyon  Range,  and  is  responsible  for  most  of  the  coast 
between  Fillmore  and  George's  Ranch.  He  contributed  also  numerous  de- 
tails in  all  parts  of  the  basin.  The  remaining  portions  of  the  shore  were 
mapped  by  me.  Some  idea  of  the  distribution  of  responsibility  for  the  maj), 
as  well  as  of  the  thoroughness  of  the  exploration,  may  be  derived  from  an 
examination  of  PI.  Ill,  where  the  routes  of  travel  are  exhibited. 

THE     PROA^O    SIIORE-I^INE. 

Below  the  Bonneville  shore-line  are  numerous  other  shore-lines,  amting 
which  one  is  cons})icuous.  The  name  Provo  was  given  to  it  on  account  of 
a  great  delta,  which  is  at  once  a  notable  feature  of  the  shore-line  and  a  prom- 
inent element  of  the  topograj)hy  of  Utah  N'alley  in  the  vicinity  of  the  town 
of  Provo.  The  shore  mark  so  far  surpasses  in  strength  all  others  of  the 
series  that  this  character  serves  for  its  identification;  and  it  has  been  recog- 
nized in  all  parts  of  the  basin  without  the  necessity  either  of  tracing  its 
meander  or  of  measuring  its  altitude.  It  has  indeed  been  recognized  with 
confidence  des})ite  conflicting  determinations   of  altitude,  for  it  is   neither 


THE  PROVO  SHORE-LINE.  127 

uniform  in  height  nor  uniform  in  its  vertical  relation  to  the  Bonneville  shore- 
line. In  a  general  way  it  is  375  feet  lower  than  the  Bonneville  shore  and 
625  feet  higher  tlian  the  water  of  Great  Salt  Lake. 

The  Provo  record  is  more  recent  than  the  Bonneville.  "^I'liis  a])pears, 
first,  from  its  state  of  preservation;  tlie  Provo  cliffs  are  the  steeper  and 
sharper  and  the  smaller  talus  lies  at  their  base.  It  appears,  second,  from 
the  absence  of  lake  sediments  on  the  surfaces  of  the  Provo  terraces.  Dur- 
ing the  formation  of  the  Bonneville  shore,  the  horizon  of  tlie  Provo  was 
sufficiently  submerged  to  receive  a  layer  of  fine  sediment;  and  a  lake  de- 
posit commensurate  in  amount  with  the  shore  drift  accumulated  in  the  Bon- 
neville embankments  would  not  escape  detection  if  it  had  rested  on  the 
terraces  of  the  Provo  shore.  The  relative  age  is  shown  also  Ijy  the  relation 
of  the  shores  to  the  outlet  of  the  lake,  as  will  be  explained  in  another 
chapter. 

The  duration  of  the  water  stage  recorded  by  the  Provo  shore  was 
greater  than  that  of  the  Bonneville  water  stage.  Although  tlie  Bonneville 
is  the  most  conspicuous  of  all  the  shore-lines,  it  does  not  exhibit  the  greatest 
monuments  of  wave  work,  but  owes  its  prominence  largely  to  its  position 
at  the  top  of  the  series,  where  it  is  contrasted  with  topographic  features  of 
another  type.  There  are  several  other  shore-lines  which  rival  it,  and,  al- 
though it  probably  outranks  in  magnitude  all  except  the  Provo,  its  discrim- 
ination would  be  a  difficult  matter  were  it  an  intermediate  member  of  the 
series.  The  Provo,  on  the  contrary,  is  rendered  conspicuous  chiefly  by  the 
magnitude  of  its  phenomena.  Its  embankments  are  the  most  massive,  and 
its  wave-cut  terraces  are  the  broadest.  Moreover,  the  Provo  Lake  was  in 
every  way  inferior  to  the  Bonneville  as  a  field  for  the  generation  of  jiowerful 
waves.  It  was  narrower  and  shallower  and  obstructed  by  larger  islands. 
To  have  constructed  shores  eciual  to  those  of  the  Bomieville,  it  must  needs 
have  existed  a  longer  time;  and  still  longer  to  have  built  its  greater  struct- 
urcis. 

OUTLINE  AND  EXTENT. 

The  outline  of  the  lower  shore  was  the  less  tortuous.  The  sinuosity  of 
the  Bonneville  shore  is  due  to  the  fact  tliat  the  water  flooded  a  large  num- 
ber of  the  narrow  trouglis  of  the  Great  Basin  and  was  partially  divided  by 


128  LAKE  BONNEVILLE. 

the  mountain  ridges.  When  the  Avater  retreated  to  tlic  I'rovo  level,  it  ;il);iii- 
doned  a  considerable  number  of  the  valleys  and  retired  on  in;iii\  jiarts  of 
the  coast  from  the  uneven  mountain  faces  to  the  smooth  contours  of  the 
alluvial  slopes.  Two  of  the  largest  bays,  the  Escalante  and  the  Snake  Val- 
ley, were  completely  desiccated,  and  so  was  a  third  part  of  the  Sevier  Des- 
ert. The  water  was  withdrawn  from  Thousand  Spring  and  Buell  Valleys, 
from  Gi'ouse  Valley  and  Park  Valley,  from  Ogden  Valley  and  Morgan 
Valley,  from  Cedar  Valley,  Rush  Valley,  and  Tintic  Valley,  and  from  both 
ends  of  Juab  Valley.  Of  the  three  straits  joining  the  Sevier  Ixtdy  with  tlie 
main  body  of  the  lake,  only  the  eastern  remained.  The  closhig  of  the  cen- 
tral and  western  straits  joined  to  the  western  peninsula  the  islands  Avhicli  ha<l 
been  constituted  by  the  MacDowell  and  Dugway  Mountains.  The  islands 
formed  Ijy  the  Promontory,  the  Cedar,  and  the  Beaver  Creek  Ranges,  were 
converted  into  peninsulas,  and  so  was  Pilot  Peak.  The  grouj)  of  islands 
south  of  Park  Valley  and  the  group  south  of  Cuidew  were  joined  to  the  niiiin- 
land;  and  it  is  possible  that  the  islands  constituted  by  the  Lakeside  Mountains 
were  united  to  the  Cedar  Mountain  peninsula.  Doubtless  many  other  hills 
that  had  previously  been  submerged  now  a})peared  as  islands ;  but  none  of 
these  were  of  great  extent,  and  the  total  numljer  of  islands  must  have  been 
greatly  diminished.  Ann)ng  the  emergent  islands  were  some  of  the  volcanic 
buttes  west  of  the  town  of  I^illmore  and  a  basaltic  mesa  southwest  of 
the  town  of  Deseret.  The  passage  from  Cache  Valley  to  the  main  body 
was  reduced  to  a  narrow  strait  only  a  few  hundred  feet  in  width,  and  the 
entrances  to  the  Utah  Lake  bay  and  the  White  Valley  bay  were  greatly 
restricted. 

SHORE  CHARACTERS. 

Li  several  respects  the  newer  shore-line  has  a  different  facies  tVoni  tiie 
older.     It  has  already  been  remarked  that  it  is  more  freshly  cut.     It  is  char 
acterized  also  by  its  l)i-oader  terraces,  by  its  deltas,  \)y  its  tufas,  and  liy  a 
peculiar  duplication  in  its  ])rofile. 

While  the  Provo  cut-terraces  are  far  broader  than  the  Bonneville,  the 
associated  sea-cliffs  are  not  so  high,  the  difference  being  occasioned,  in  part 
at  least,  by  the  relations  of  the  two  water  surfaces  to  the  general  slojjc.    If  a 


•J  S. GEOLOGICAL   SURVEY 


LAKE  BONNEVILLE,    PL-Xffl. 


42 


^^L. 


39' 


38' 


113° 


112' 


nx° 


-■i  4a' 


H41= 


112  " 


MAT  OF 

nONXKN'lLLi; 


XTRNT   AT   rili;   UATK 
oJ'the 

'ROVO  SHOP.EI.INK 

IVovo  vs'alor  :vrea  iii  blue 

I  I  I  I  Miles. 


HI' 


38° 


JuUiw  Uipii  Atu.Iilh 


Diaira  byti  Thompsc 


TIIK  PliOVO  TERRACES. 


129 


profile  \k'  drawn  across  any  of  the  valleys  occupied  by  the  lake,  it  will  be 
found  to  be  broadly  U-shaped.  "^I'he  Hoor  of  each  valley  is  nearly  flat ;  and 
the  alluvial  slopes  at  tlie  sides,  rising-  very  gently  at  first,  gradually  in- 
crease their  inclination  until  they  join  tlie  acclivities  of  the  mountains.  The 
Bonneville  and  Provo  shores  are  so  related  to  the  valleys  that  their  differ- 
ence of  a  few  hundred  feet  of  altitude  corresponds  to  a  general  and  notable 
difference  in  the  slopes  of  the  land  at  their  margins.  The  Provo  waves, 
attacking  comparatively  gentle  slopes,  produced  terraces  of  great  width, 
as  the  companions  of  cliffs  with  but  moderate  height.  Floors  200  to  400 
feet  broad  are  of  frequent  occurrence ;  and  in  one  place  a  cliff  75  feet  high 
overlooks  a  terrace  750  feet  wide. 


FiG.  24. — Limt'stoui}  buttu  uear  lie ddiny;  Spriug,  Giv.at  Salt  Lake  Desert ;  au  island  at  the  Provo  stage. 

Deitas.-The  abundance  of  deltas  on  the  Provo  coast  requires  for  its  ex- 
planation a  considerable  chapter  of  the  history  of  the  lake.  It  has  already 
been  remarked  that  the  principal  streams  tributary  to  the  basin  rise  at 
the  east.  In  flowing  westward  each  of  them  encounters  one  or  more 
mountain  ranges,  across  which  it  passes  in  a  deep  and  narrow  defile  or  can- 
yon. The  drainage  system  is  older  than  the  lake;  and  this  series  of  canyons 
was  completed  Ijy  the  streams  before  the  Bonneville  epoch,  so  as  to  form 

MON  I ^9 


130  LAKE  BONNEVILLK. 

]);irt  of  tlie  system  of  valleys  flooded  ])y  tin;  lake.  When  the  water  first 
rose  to  the  Bonneville  level,  it  set  back  a  number  of  miles  into  each  of  the 
canyons;  and  in  some  instances  extended  beyond  the  first  mountiuu  i-inge, 
forming  small  bays  on  the  eastern  side.  During  the  period  represented  by 
the  Bonneville  shore-line,  the  detritus  brought  by  the  rivers  Avas  tlu-ovvn  into 
these  bays  and  inlets  and  gradually  reduced  their  dimensions.  A  few  of 
the  smaller  inlets  were  completely  filled;  and  in  three  or  four  instances 
small  deltas  were  projected  into  the  lake;  but  the  remainder  of  the  canyons 
retained  the  character  of  inlets  until  the  water  fell.  At  the  beginning  of  the 
Provo  epoch  it  is  probable  that  nearly  all  of  the  larger  canyons  admitted 
short  estuaries,  but  of  this  there  is  no  definite  record.  If  such  existed,  they 
were  quickly  filled  by  alluvium, — the  preexisting  accumulations  at  the  heads 
of  the  canyons  aff'ording  an  abundant  supply  ready  at  hand.  The  fomia- 
tion  of  a  delta  in  the  open  lake  must  have  begun  at  the  mouth  of  each  can- 
yon soon  after  the  establislmient  of  the  water  stage;  and  it  was  continued 
until  the  close  of  the  Provo  epoch.  The  water  surface  then  fell  once  more, 
and  the  lowering  of  the  mouths  of  the  streams  caused  them  to  begin  the 
erosion  of  the  deltas ;  but  the  broad  terraces  built  on  the  open  plain  were 
not  so  easily  effaced  as  the  alluvial  dejjosits  within  the  narrow  canyons,  and 
the  destiiictive  activity  of  the  streams  has  accomplished  oid}-  the  opening 
of  teiTaced  channels  through  them. 

The  channeling  of  the  deltas  was  accompanied  by  the  construction  of 
other  deltas  at  lower  levels,  so  that  each  river  course  is  margined  by  a  series 
of  deltas  embodying  a  portion  of  the  history  of  the  progressive  changes  of 
the  lake.  In  the  discussion  of  these  series  in  a  later  section,  the  several 
deltas  of  the  Provo  shore  will  receive  separate  mention  and  description. 

Calcareous  tufa  has  been  found  in  association  with  many  of  the  shore- 
lines and  was  }jrobably  deposited  in  some  amount  at  all  stages  of  the  lake. 
It  is  exceptionally  abundant  at  the  Provo  level,  but  it  will  be  more  con- 
venient to  describe  its  occurrence  in  a  special  section  devoted  to  the  subject 
of  tufa. 

The  Underscore.- Where  tlic  Provo  watcr  mark  is  a  work  of  excavation,  its 
characteristic  profile  includes  two  sea-cliffs  and  two  terraces.  The  upper 
cliff  is  the  greater  of  the  two,  and  the  terrace  at  its  foot  is  the  broader  ter- 


THE  UNDEKSCORK.  131 

race.  The  lower  terrace  is  rarely  more  than  a  twentieth  part  as  great  as 
the  upper,  and  in  many  places  it  could  not  be  detected.  The  vertical  space 
between  the  two  shelves  is  estimated  to  range  from  five  to  twenty  feet;  at 
the  sole  point  of  measurement  it  is  six  feet.  The  main  terrace  is  conspicu- 
ously distinguished  by  its  flatness.  At  no  other  stage  of  the  lake  have  the 
waves  carved  out  so  level  a  platform.  In  its  broader  examples  the  lake- 
ward  slope  is  barely  perceptible  to  the  eye;  and  at  no  i)oint  does  the  total 
descent  from  the  foot  of  the  upper  cliff  to  the  crest  of  the  lower  exceed  five 
feet.  The  lower  terrace  has  no  idiosyncrasies  aside  from  its  association  with 
the  upper,  but  that  peculiai'ity  has  caused  it  to  be  styled  in  the  field  note- 
books "the  underscore,"  and  it  will  be  convenient  to  retain  the  designation. 
Though  not  iiniversally  discernible,  yet  it  is  so  persistent  a  feature  as  to  be 
found  serviceable  in  the  identification  of  the  Provo  shore  at  doubtful  points. 

EMBANKMENT    SERIES. 

Wliere  the  water  mark  consists  of  works  of  construction  its  characters 
are  less  constant.  As  a  rule,  the  bays  of  the  Provo  coast  are  spanned  by 
single  bars;  and  its  spits,  like  those  of  the  Bonneville  shore,  are  apparently 
simple  in  structure;  but  in  a  few  instances  the  accumulations  in  bays  are 
observed  to  consist  of  two  bars  with  the  outer  lower  than  the  inner.  The 
difference  of  height  was  never  subjected  to  measurement;  but  was  estimated 
to  be  about  fifteen  feet.  At  Dove  Creek  (see  PI.  XXII)  the  shore  exhibits 
two  wave-built  terraces,  of  which  the  outer  and  later  formed  is  14  feet  lower 
than  the  inner. 

On  Terrace  Mountain,  a  few  miles  south  of  Ombe  station,  the  Provo  em- 
bankments in  a  small  bay  are  separated  after  the  manner  of  the  Bonneville 
embankments  in  Snake  Valley,  and  include  six  distinct  bars  with  a  faint 
suggestion  of  four  others.  A  profile  of  these  is  given  in  Fig.  3  of  PI.  XIV. 
Fig.  1  of  the  same  plate  exhibits  the  cut  terrace  with  the  underscore;  Fig.  2, 
the  double  bay  bar. 

In  Tooele  Valley  the  Provo  presents  the  most  remarkable  expansion 
of  a  shore  record  that  has  anywhere  been  preserved.  During  that  epoch  the 
valley  contained  an  open  bay  receiving  storm  waves  from  the  broadest  por- 
tion of  the  lake.     The  principal  excavation  was  from  the  alluvial  slopes  of 


132  LAKE  BONNEVILLE. 

the  western  base  of  the  0<iuirrli  mtmntaiiis,  ;nul  tlic  material  was  swept 
soutliward  to  th(!  shaUow  head  of  the  bay,  where  it  was  built  into  a  series  of 
bars  stretcliiny  from  sliore  to  shore  witli  sweeping  curves.  In  this  series  65 
inihvichial  bars  have  been  counted  and  their  aggi-egate  width  is  more  than  a 
mile.  Their  order  of  position  is  necessarily  the  order  of  their  formation; 
and  their  i)rofile  (PI.  XIV,  Fig.  4)  exhibits  in  consecutive  order  the  local 
variations  of  the  relation  of  water  to  land  during-  the  Provo  epoch. 

The  double  terraces,  the  double  bay  bars,  the  bar  series  of  Terrace 
Mountain,  and  the  bar  series  of  Tooele  Valley,  constitute  the  ^\'liole  of  our 
information  with  regard  to  the  oscillations  of  the  lake  during  the  Provo  epoch ; 
and  all  effort  to  coi-relate  them  and  deduce  a  consistent  history  has  failed, 
lu  the  discussion  of  the  Bonneville  })rofiles,  it  was  found  that  the  more 
extended  series  was  represented  in  the  less  extended  only  by  its  highest 
members,  the  minima  of  the  profiles  disappearing  as  they  were  condensed. 
If  the  same  relation  subsists  between  the  Provo  profiles,  then  each  member 
of  the  Terrace  Mountain  series  should  be  foiuid  to  coi-respond  to  some  max- 
imum of  the  Tooele  Valley  series.  The  comparison  is  necessarily  begini  Ijy 
equating  the  highest  member  of  one  locality  Avitli  the  highest  member  of  the 
other: — that  is,  by  saying  that  the  Terrace  Mountain  r  and  d  are  equivalent 
to  the  Tooele  Valley  C  and  D.  Tlien  a  and  h  of  the  Terrace  profile  should  be 
represented  by  maxima  to  the  left  of  C  in  the  Tooele  ])rofile;  but  the  only 
maximum  of  this  kind  is  at  A,  and  is  too  low  by  nearly  30  feet.  The  ter- 
race from  E  to  F  may  be  compared  without  gi-eat  incongruity  with  the  bar 
e;  but  the  maximum  at  H  is  20  feet  too  high  to  be  represented  by  the  bar 
/  Similar  difficulties  prevent  the  correlation  of  the  Ten-ace  profile  with  the 
double  bar,  Fig.  2;  but  they  do  not  arise  when  the  latter  is  compared  with 
the  Tooele  profile.  The  higher  bar  of  the  pair  may  fairly  be  taken  as  the 
equivalent  of  the  Tooele  group  from  A  to  F,  and  the  lower  bar  may  represent 
the  emljankments  from  G  to  I. 

The  wave-cut  terrace  and  underscore  (Fig.  1)  have  no  sj-mpathy  with 
any  bar  gronj)  except  the  simple  pair.  It  is  ]n-obable  that  the  greater  and 
higher  bar  K  was  in  whole  or  part  the  contemporary  of  the  terrace  M ;  and 
it  is  possi])le  that  the  minor  bar  L  was  the  contemporary  of  the  underscore. 

Though  the  wave-cut  terraces  and  the  Tooele  Valley  bar  series  sever- 


PROBLEMS  OF  CORRELATION.  133 

ally  accord  with  the  double  bars,  tliey  do  not  harmonize  with  each  other. 
Upon  the  assumption  that  each  records  the  oscillations  of  the  water-surface, 
the  deduced  histories  are  different.  The  exceptional  flatness  and  extreme 
breadth  of  the  upper  terrace  seem  to  show  that  the  waves  were  for  a  long 
time  at  a  unifomi  horizon,  or  else  that  the  latest  work  of  excavation  was  at 
so  low  a  level  that  all  terraces  of  anterior  production  were  undercut  and 
obliterated ;  the  underscore  appears  to  re})resent  a  brief  lingering  after  the 
main  terrace  had  been  finally  dried.  The  Tooele  Valley  profile,  on  the 
other  hand,  indicates  a  gradual  rise  of  40  feet  from  the  base  of  the  bar  A  to 
the  upper  teiTace  B,  followed,  first,  by  a  tolerably  uniform  high  stage  BF, 
and,  second,  by  a  stage  GI  ten  or  fifteen  feet  lower.  If  the  breadth  of  the 
bars  be  taken  as  a  time  scale,  the  liigher  stage  had  twice  the  duration  of  the 
lower,  but  occupied  somewhat  less  time  than  the  gradual  rise  preceding  it. 
If  the  production  of  an  individual  bar  be  taken  as  the  unit  for  time-scale, 
the  higlier  stage  had  two  and  one-half  times  the  duration  of  the  succeeding 
low  stage  and  tlu-ee  times  the  duration  of  the  antecedent  rise.  If,  now,  we 
correlate  the  central  group  of  Tooele  bars  with  the  main  wave-cut  terrace, 
and  correlate  the  outer  group  of  bars  with  the  underscore,  we  find  two  diffi- 
culties. In  the  first  place,  the  underscore  represents  but  a  small  fraction  of 
the  period  of  wave  action  under  consideration,  while  the  outer  series  of 
Tooele  bars,  upon  any  plausible  basis  of  estimate,  represents  a  relatively  large 
fraction.  In  the  second  place,  the  progressive  rise  implied  by  the  Tooele 
profile  has  no  expression  in  the  wave-cut  terraces,  where  its  effect  would  be 
to  impair  the  definition  of  the  outer  edge  of  the  main  terrace  and  contra- 
vene its  characteristic  flatness.  There  appears  then  no  way  in  which  to 
reconcile  the  various  analytic  naanifestations  of  the  Provo  shore  on  the  hy- 
pothesis that  the  recorded  oscillations  are  purely  those  of  the  water  surface. 
The  presumption  is  therefore  in  favor  of  the  alternative  hypothesis  that 
there  were  differential  movements  of  the  earth's  crust  witliin  the  basin  dui'- 
ing  this  epoch.  Unfortunately,  the  data  are  too  meager  for  the  discussion 
of  this  hypothesis. 


134  Lake  bonne villb. 

THE  MAP. 

During  the  prosecution  of  the  field  work,  no  attempt  was  made  to  ob- 
tain the  data  necessary  for  mapping  the  Provo  shore-Hne ;  hut  the  note- 
books contain  so  many  incidental  references  to  its  position  that  it  has  been 
found  possible  to  construct  a  map  not  grossly  eiToneous.  The  reader  is 
warned  that  the  outline  delineated  in  PI.  XIII  is  approximate  only.  A 
similar  qualification  applies  to  estimates  of  area.  The  water  surface  at  the 
Provo  stage  had  an  approximate  extent  of  13,000  square  miles,  11,500  be- 
longing to  the  main  body  and  1,500  to  the  Sevier  body. 

THE    STANSBURY    SHORE-LINE. 

From  the  Provo  water  line  to  the  margin  of  Great  Salt  Lake,  the  de- 
scent is  more  than  600  feet.  From  the  same  line  to  the  Bonneville  shore 
the  ascent  is  less  than  400  feet.  In  the  upper  space  all  the  conspicuous 
lacustrine  features  are  referable  to  shore  action,  but  there  are  subordinate 
evidences  of  sedimentation.  In  the  lower  space  lake  sediments  predominate, 
giving  their  peculiar  smoothness  to  the  surface,  and  the  shore  tracings  are 
relatively  unimportant.  Upon  any  jjrofile  a  considerable  number  of  shores 
can  be  recognized  below  the  Px'ovo;  and  it  is  probable  that  a  system  of 
levelings  would  enable  these  to  be  correlated  in  a  consistent  system.  This 
has  not  been  done,  and  only  a  single  one  has  been  widely  recognized.  That 
one  is  distinguished  merely  by  the  greater  magnitude  of  its  cliffs  and  em- 
bankments, but  is  not  sufficiently  accented  to  be  everywhere  identified.  It 
is  called  the  Stansbury  shore-line.  Its  strongest  delineation  is  upon  Stans- 
bury  Island,  where  owing  to  local  conditions  it  rivals  the  Provo  shore  in 
definition  and  surpasses  the  Bonneville.  In  abundance  of  tufaceous  deposit 
it  probably  ranks  next  to  the  Provo, 

Its  height  was  measured  at  two  points  only.  On  the  west  side  of  the 
Terrace  Range  it  lies  310  feet  below  the  Provo  shore;  and  at  the  north  end 
of  the  Aqui  Range  346  feet.  At  the  latter  locality  it  was  found  to  be  330  feet 
above  the  level  of  Great  Salt  Lake.  It  is  thus  seen  to  divide  about  equally 
the  interspace  betwen  the  Provo  shore  and  the  shore  of  Great  Salt  Lake. 

At  the  time  of  its  formation  the  maximum  depth  of  the  lake  was  only 
about  half  as  great  as  at  the  Provo  date ;  and  the  water  surface  was  corre- 


Li  S. GEOLOGICAL    SUF.VEY 


Ii/vI<E  BONNEVILLE      PL.  X'/ 


MAP  OF 


SHORE   KMljANKMKNTS, 


Near  Gi-aiilsvilli- .  llali 


Hv    II    A    WhiMli 


Fig.  Pruiilc,    .-1     A'    B 


A 

BoTin^yiiLe. 

.;}^^-T^^ 

? 

mm 

^ 

I^ 

ip^^i^ 

3v^-o 

-^^liiA^ 

S 

-^ 

Veriical  Scale  tivice  the  MoTizontcil 


Julius  Bi<;n  ^Co.lilK 


Drawn  by  G  Thumpei, 


STANSBUEY  SHOEE-LINB.  135 

spondingly  diminished.  The  constructive  waves  were  therefore  less  power- 
ful and  the  time  necessary  for  the  performance  of  an  equal  work  was  longer. 
There  is  good  evidence,  however,  that  the  period  of  time  represented  by  this 
shore  is  shorter  than  that  represented  by  the  Provo.  The  body  of  water 
covering  the  Se^-ier  Desert  during  the  Provo  epoch  was  smaller  than  the 
body  occupying  the  Great  Salt  Lake  Desert  at  the  Stansbury  epoch ;  and 
yet  the  shore  phenomena  by  which  it  is  outlined  are  upon  a  far  larger  scale 
than  any  exhibited  l)y  the  Stansbury. 

The  water  was  at  this  time  withdrawn  from  the  Sevier  Desert,  but  cov- 
ered the  main  portion  of  the  Great  Salt  Lake  Desert.  It  washed  the  foot 
of  the  Wasatch  and  extended  within  a  few  miles  of  the  western  line  of  the 
Bonneville  shore,  but  was  excluded  from  most  of  the  bays  at  the  north  and 
south.     Its  total  area  was  in  the  neighborhood  of  7,000  square  miles. 

THE    INTERMEDIATE    SHORE-IjINES. 

In  every  locality  where  the  Bonneville  and  Provo  shores  are  marked 
by  considerable  accumulations  of  shore  drift,  the  whole  of  the  intermediate 
slope  is  similarly  characterized.  In  every  locality  where  the  Bonneville 
and  Provo  shores  give  evidence  of  excavation,  the  intervening  space  is  com- 
pletely occu})ied  by  similar  evidence,  but  the  phenomena  are  in  this  case 
less  conspicuous. 

DESCRIPTION    OF   EMBANKMENTS. 

Grantsviiie.-If  the  reader  will  turn  to  PI.  XV,  which  represents  a  tract  of 
country  a  few  miles  south  of  the  town  of  Grantsville,  he  will  see  that  an 
angle  of  the  valley,  containing  a  bay  of  the  ancient  lake,  occasioned  the 
local  accumulation  of  large  embankments.  By  studying  the  contours  of 
the  map,  or  by  referring  to  the  accompanying  profile,  he  will  see  that  these 
embankments  have  their  crests  at  various  levels,  the  order  of  height  being 
also  the  order  of  horizontal  position.  The  Provo  embankment  was  can-ied 
entirely  across  the  bay,  so  as  to  complete  a  bar;  and  the  same  is  true  of  the 
one  next  to  it  in  the  series.  The  development  of  the  other  embankments 
was  arrested  while  they  were  yet  spits.     Box  Elder  Creek,  which  was  tribu- 


136  LAKE  liONNEVILLE. 

tary  to  the  bay,  has  its  modern  course  deflected  by  the  spits,  and  has  opened 
a  passage  through  the  bay  bars.  Each  of  these  enibankuients  is  tlie  product 
of  essentially  the  same  comV)ination  of  local  conthtions.  At  each  of  the 
represented  stages  the  shore  drift  derived  from  a  long  alluvial  slope  at  the 
north,  beyond  the  field  of  the  map,  was  carried  southward  toward  the  edge 
of  the  bay  and  there  accumulated  in  a  long  embanlcment,  built  in  the  deep 
water  of  the  bay  on  a  line  tangent  to  the  shore  at  the  north.  Between  the 
Bonneville  and  the  Provo  there  are  four  principal  embankments;  and  it  was 
a  natural  assumption,  made  at  an  early  stage  of  the  investigation,  tliat  each 
of  these  embankments  recorded  the  work  accomplished  by  the  waves  at  a 
stage  represented  by  the  height  of  its  ci'est.  This  assumption  was  for  a 
time  unquestioned,  but  later  developments  led  to  doubt  of  its  validity;  and, 
in  order  to  test  it,  a  systematic  collection  of  shore  data  was  undertaken. 
Localities  were  sought  where  the  configuration  of  the  lake  bottom  favored 
the  construction  of  shore  embankments  at  all  levels  from  the  Bonneville  to 
the  Provo,  and  at  such  localities  contour  maps  Avere  made  and  profiles  were 
measured  with  the  spirit-level.  By  means  of  these  maps  and  profiles,  taken 
in  connection  with  the  details  of  structure  observed  at  the  same  locality,  the 
general  history  of  the  Intermediate  shore-lines  was  developed,  but  the  orig- 
inal assumption  was  overthrown. 

In  order  to  present  this  liistory  to  the  reader,  with  the  evidence  upon 
which  it  rests,  it  will  be  necessary  to  make  him  acquainted  with  a  selected 
series  of  the  maps,  which  series  has  been  reproduced  in  the  accompanying 
plates. 

preuss  vaiiey.-Pl.  VIII  rcpreseuts  eight  miles  of  the  eastern  side  of  Preuss 
Valley.  At  the  right  stand  the  rocky  spurs  of  the  Frisco  Mountains,  and 
against  their  base  the  stream  drift  from  the  canyons  is  piled  in  great  alluvial 
cones.  While  the  lake  occupied  the  valley,  the  fi)rm  of  its  shore  was  given 
by  the  contours  of  the  alluvium,  each  great  cone  occasioning  a  rovmded 
cape,  and  each  interval  between  the  cones,  a  bay.  From  tlnee  of  the  capes 
the  currents  were  deflected  in  such  way  as  to  accunudate  the  shore  drift  in 
a  system  of  embankments, — and  this  at  all  levels  from  the  Bonneville  to  the 
Provo.  Pis.  XVI,  XVII  and  XVIII  show  the  details  of  the  thi-ee  localities 
of  accumulation. 


U  S. GEOLOGICAL    SURVEY 


LAKE  BONNEVILLE      PLXVI 


MAP  OF  THE 

NORTH     GROUP 

OF 

SHORE  emuankment; 

IN 

PREUSS    VALLEY,   UTAH. 


By    C;.  K.    Uilberl. 


1000  2000 


10- feet      0?Titours  - 


;^_::.^.i^'^:?^*^ 


VIEW      AS      SEEN       FROM       THE     SOUTH 


.Jul.ua  Bii-i.  Jt  ti.liOi 


Drawn  bv  C  Thoropsi 


U  S. GEOLOGICAL   SURVEY 


uAflE   BONNEVILLE      PL  X\'n 


MAP  OF  THE 

MIDDLK    ('MOW 


SlIORK   EMIJAXKMKXTS. 


PHKl'SS    VAr.LKV.  r'L\JI 


Bv  (J    K    (iillxTt 


iOOO 

SCALE    bB= 


10  CO 

I 


FEET 


lO/Wl      liinU'UiK 


BonneMllr 


hill   1        rrofiLc     u.s    seen      from      t hi:       South 
rerllitil     \til/r     id'llhir   Ihf   Hi'ii/.oil  In  I 


Ulujs  IJi(Mi  ftCo.hUi 


Di  :(wu  W  li  Tliuuiliinn 


U  S. GEOLOGICAL    SURVEY 


LAKE  BONNE'-ILLE      PLJ^'in 


MAP    OF    THE 

sorrii   (iRoiip 

OF 

S II 0 K  K   E MBAXKM  EN  T  S  , 
PREUSS     VALLEY,  UTAH, 

Bv    (;      K      Gilbert 


iOOO  o 

SCALE    f  ^  ^   ^  -^  ^ 


1000  £000 

— !    FEET 


JO  -  /ef/      (o  n  /  o  u  rs- 


Pi'oiile    as  seen     ti-oni      (he     .Kouth 
Tertnuil  Saxl^  <loubh  the Bonxonttd  , 


.luliua  Rien  &  l.o.hOi 


Drawn  bvG  Tlioinps 


Embankments  of  the  intermediate  shore-lines.      137 

The  snowpiow.-A  siiTiilar  compound  embankment,  but  on  a  grander  scale, 
was  formed  at  the  southern  opening  of  the  strait  joining  the  two  principal 
bodies  of  the  lake.  Its  general  relations  appear  on  1*1.  XXXI  and  its  de- 
tails on  PI.  XIX.  The  shore  drift  in  this  case  came  from  the  east,  being 
derived  from  a  great  alluvial  slope  formed  by  the  coalescence  of  many- 
cones  from  the  Simpson  Mountains.  The  embankments  into  which  it  was 
built  are  characterized  by  the  V-form,  and  are  so  jjiled  one  upon  another  as 
to  have  suggested  the  name  Snowplow,  by  which  the  group  was  distin- 
guished in  the  field  notes. 

Stockton  and  Weiisviiie.-The  embankmeuts  at  Stockton  (PI.  XX)  are  of  a  dif- 
ferent type,  having  lieen  tlu'own  across  a  strait  and  not  merely  projected 
from  a  shore.  That  of  the  Bonneville  stage  is,  however,  exceptional,  run- 
ning athwart  the  others  in  the  form  of  a  broad  spit ;  and  those  of  the  Prove 
stage,  which  fall  without  the  field  of  the  map  on  the  south  side,  are  typical 
bay  bars.  A  perspective  view  of  the  field  of  this  map  is  given  in  PI.  IX, 
and  a  profile  of  the  contiguous  Provo  bay  bars  in  PI.  XIV.  The  embank- 
ments at  Wells^^lle  in  Cache  Valley  (PI.  XXI)  are  of  the  same  type  as  those 
near  Grantsville,  but  are  less  perfectly  preserved.  A  mountain  stream  flow- 
ing across  them  has  opened  a  wide  channel ;  and  the  exti'emities  of  two  em- 
baidiments  have  been  truncated  by  land  slides. 

Dove  creek.-A  group  of  cmbaukinents  near  Dove  Creek,  represented  in 
PI.  XXII,  is  somewhat  similar  to  the  Snowplow,  but  the  material  was  in 
large  part  torn  by  the  waves  from  solid  rock,  and  not  merely  dug  from 
alluvium.  It  first  traveled  northward  along  the  coast  from  which  it  was 
cut ;  and  then  turning  abruptly  to  the  northwest,  was  built  into  terraces 
upon  another  face  of  the  same  island. 

COMPARISON    OF  EMBANKMENTS. 

For  the  purpose  of  comparison,  the  vertical  elements  of  all  these  local- 
ities have  been  assembled  on  a  single  page  in  PI.  XXIII.  The  data  are  so 
diverse  in  character  that  they  are  not  easily  comjjared  by  means  of  profiles 
on  a  natural  scale,  and  an  attempt  has  therefore  been  made  to  eliminate  all 
accessory  features  and  represent  merely  altitudes  and  quantities  of  wave 
work.     In  each  of  the  profiles  of  the  plate,  a  sti'aight  line  inclined  at  45°  is 


138  LAKE  BONNEVILLE. 

made  to  stand  for  the  original  surface  upon  which  the  embankments  were 
built.  The  horizontal  distance  of  each  point  of  eacli  profile  from  this  base 
represents  the  total  quantity  of  material  added  to  the  shore  at  that  locality 
and  level.  In  the  case  of  the  Stockton  diagram,  Fig.  6,  it  was  impossil^le  to 
represent  comparative  quantities  of  material,  and  only  altitudes  are  ex- 
pressed. At  the  north  end  of  Preuss  Valley  the  lower  members  were  not 
mapped,  because  they  lay  at  an  inconvenient  distance  from  the  upper ;  and 
the  profile,  Fig.  3,  is  thei-efore  incomplete.  The  profile  is  additionally  ex- 
ceptional in  that  it  is  doubled,  to  represent  two  series  of  embaiLkments  dif- 
fering in  date  of  fonnation.  The  earlier  series  is  (h-awn  at  the  left,  and  the 
later,  which  in  part  overlies  it,  at  the  right.  Fig.  5  represents  a  profile 
measured  at  Cup  Butte,  five  miles  northwest  of  the  Snowplow.  In  this  case 
the  vertical  element  only  is  valuable  for  comparison,  because  the  upper  and 
lower  portions  of  the  slope  were  not  similarly  disposed  with  reference  to  the 
waves.  The  lower  received  no  deposit,  but  exhibits  the  rock  of  the  butte 
carved  in  terraces  and  cliffs.  Fig.  10  represents  the  gi-eat  embankment  at 
the  Point  of  the  Mountain  south  of  Salt  Lake  City. 

The  vertical  measurements  for  the  profile  in  Fig.  7  were  made  by  means 
of  two  mercurial  barometers,  one  of  which  was  read  at  shoi*t  intervals  at  a 
station  near  by,  while  the  other  was  carried  from  point  to  point.  At  Cup 
Butte,  Fig.  .5,  the  measurement  was  by  means  of  a  hand-level  attached  to  a 
Jacob's  staff",  the  unit  of  the  instrument  having  been  detennined  experiment- 
ally by  comparison  with  the  surveyor's  level.  The  remaining  profiles  were 
measured  with  a  s})irit-level. 

The  profiles  are  an-anged  upon  the  page  in  the  order  of  geographic 
position.  The  three  groups  in  Preuss  Valley  fall  within  a  radius  of  tlu-ee 
miles.  The  Snowplow  and  Cup  Butte  groups  are  100  miles  farther  north 
but  are  separated  from  each  other  by  five  miles  only.  The  Grantsville 
and  Stockton  groups  are  10  miles  apart  and  are  45  miles  north  of  the 
Snowplow.  The  Wellsville  and  Dove  Creek  groups  are  isolated.  They 
are  80  miles  apart  and  each  is  90  miles  distant  from  Grantsville,  the  nearest 
of  the  other  localities.  The  Point  of  the  Mountain  is  separated  from  the 
Stockton  group  by  an  interval  of  more  than  20  miles,  including  a  mountain 
range. 


U  S. GEOLOGICAL    SURVEY 


U\KE  BONNEVlLLi;      FL.XK 


W    \\\,    v,\\\„\\ 


MAP  OF 

[1-:  SNOWPLOW, 

A 

1M)1'  SlIOHK  THUIUCKS 

near  tliP 

KD.l'TAH. 


SCALE    t 


lO-fefi    Contours 


VIEW     FROM    THE     NORTHWEST. 


luliiis   ilu-ii   \  i'o.lllll 


Dr.n*i,  bv  li  Th"iup>nn 


U  S. GEOLOGICAL    SURVEY 


LAKE  BONNEVILLE      PZyj^ 


MAP  OF  THE  PASS 


bPiwHon 


RUSH  AND  TOOELE  VALLEYS.  ULUl. 


ShoM-ind  the 


NViVVE  HUILT  B.UJRIER 


Rv    H    A    VVhoelei- 


aOOO  Q  100  0  2O00 

SCALE    III  I  I  CCCT 

l/6>  -fegl.     Contott.rs  . 


\>Ttiral    Spctio  n    from    O"    to    H  u  s  li    L  n  Ke 
VeftfitiL      Scale       tionbJe      (fie     //orixontul 


*  ISicn  S.Co,lia, 


Qrowu  by  GTIiompHOn 


S.GEOLGOICAL    oLIRVr-'i 


LAI-LE   BoMNE-.OLLE      PL  773 


VIEW     FROM    THE    EAST 


^^^^te.^ 


-lulius  Ripn  A  Cu.i.tJ, 


wn  by  C.Tli..inpson  and  W  H.Holtn 


U  S-GEOLOOrcAL    SUPirEY 


LAKE  BONNEVILLE      PLXSH 


MAP  OF 

SHORE     TERRACES 

NeaT  Dove   Ci'cpk,  Ulnh 
Bv  Gilbert  Thoinpsim 

SCALE  ° 


1000 

I — 


2U00 


'•^'••■■^'^\ 


/O/eel    t'imlniirs 


Boitri^,  ,  II  f 


'■  N\\\SvVVAvy- 


VIEW       FFfOM      Th'e"    s'ouf  H  EAS'f'"  "  ■ 


-     ,  ,    ^  ^>  \\^\>.v\%<- 


liliurt  tlii-n  A  Co. Ml, 


Drawn  bv  li  Tli.>iri 


ATTEMPTS  AT  CORRELATION.  139 

Having  thus  assembled  the  data,  let  us  now  endeavor  to  obtain  a  clear 
conception  of  the  questions  to  be  answered  by  their  comparison.  At  the 
Grantsville  locality  the  shore  di-ift  is  built  into  a  small  number  of  large, 
definite,  individual  embankments,  differing  in  height.  The  analogy  of  the 
Bonneville  and  Provo  shores  suggests  the  hypothesis  that  each  of  these  em- 
bankments was  produced  by,  and  therefore  represents,  a  prolonged  mainte- 
nance of  the  water  surface  at  a  corresponding  height.  Under  this  hypothesis 
there  should  have  been  accmuulated  at  each  of  the  other  localities  during 
this  time  a  corresponding  embankment;  and  if  all  the  embankments  remain 
undisturbed  in  their  original  position,  a  complete  correlation  should  readily 
be  made  out.  For  each  of  the  principal  embankments  at  Grantsville  there 
should  be  found  a  representative  at  the  same  height  in  each  of  the  other 
localities.  If  such  correspondence  is  not  found,  it  is  necessary  either  to 
abandon  the  hypothesis,  or  else  to  supplement  it  by  the  assumption  that  the 
relations  of  the  embankments  were  deranged  by  differential  movements  of 
the  earth's  crust  occurring  during  the  general  period  of  their  formation. 

Examining  now  another  locality,  as,  for  example,  the  Wellsville,  Fig.  8, 
we  find  that,  although  it  exhibits  a  small  number  of  large  individual  em- 
bankments, the  altitudes  of  these  do  not  correspond  each  to  each  with  the 
altitudes  of  the  Grantsville  embankments.  However  the  comparison  is  made 
this  disparity  appears.  In  the  plate  the  Bonneville  horizon  is  assumed  as  the 
common  zero  for  the  vertical  elements  of  the  profiles.  This  assumption  is 
purely  arbitrary,  and  Avas  not  adhered  to  in  making  the  comparisons.  In 
order  to  test  the  matter  fully,  each  group  of  embankments  was  represented 
on  a  sheet  of  transparent  paper  by  a  system  of  parallel  lines  whose  intervals 
were  drawn  to  a  scale,  so  as  to  agree  with  the  vertical  intervals  of  the  em- 
bankments. These  transparent  sheets  were  then  superposed  in  pairs  and 
other  combinations,  and  were  tentatively  adjusted  in  numerous  ways,  in  the 
hope  of  discovering  occult  correspondences. 

Only  one  element  of  order  was  discovered.  A  horizon  from  15  to  25 
feet  below  the  Bonneville  (marked  a  on  the  plate)  is  discernible  in  eight  of 
the  ten  localities.  With  this  single  exception,  there  are  no  correspondences 
which  can  not  be  referred  to  fortuitous  coincidence.  Not  only  is  the  series 
of  altitudes  different  at  each  locality,  but  the  number  of  embankments  varies 


140  LAKE  BONNEVILLE. 

from  place  to  place.  It  is  evident,  therefore,  that  the  hypothesis  of  persistent 
water  stages  is  tenable  only  with  the  addition  of  a  h}"]iothesis  of  contempf)- 
raneoxis  dis})lacement;  and  the  question  arises  whether  we  have  any  means 
of  subjecting-  this  phase  of  it  to  test. 

HYPOTHESIS  OF  DIFFERENTIAL  DISPLACEMENT. 

The  supplementary  hypothesis  is  not  a  priori  a  violent  one.  As  will  be 
set  forth  in  a  following  chapter,  our  investigation  has  fully  demonstrated  tlmt 
the  Bonneville  shore-line  is  no  longer  of  equal  altitude  at  all  points,  but  varies 
within  the  region  comprising  these  localities  through  a  range  of  more  than 
100  feet.  The  same  has  been  shown  with  reference  to  the  Provo  shore-line; 
and  it  has  also  been  shown  that  a  part  of  the  Bonneville  derangement  oc- 
curred before  the  Provo  epoch.  In  the  series  of  localities  represented  by 
the  profiles,  the  interval  between  the  Bonneville  and  Provo  shore-lines  ranges 
from  345  feet  to  400  feet,  exhibiting  a  difference  of  55  feet.  It  is  therefore 
easy  to  believe  that  the  localities  may  have  undergone  relative  displacement 
after  the  construction  of  certain  of  the  Intennediate  embankments  and  prior 
to  the  construction  of  others,  or  even  that  local  changes  of  water  level  may 
have  been  thus  occasioned  at  one  locality  while  the  process  of  shore  forma- 
tion was  continuous  at  another.  The  possibility  of  confusion  thus  intro- 
duced seems  at  first  unlimited,  and  a  rigorous  test  of  the  hjqiothesis  would 
be  difficult  were  it  not  for  a  fortunate  circumstance.  The  .surveyed  locali- 
ties include  several  pairs,  the  members  of  which  are  so  closely  associated 
geographically  that  there  is  a  strong  presumption  against  their  ha\'ing  been 
affected  discordantly  by  contemporaneous  earth  movements.  The  middle 
and  southern  localities  of  Preuss  Valley,  Figs.  1  and  2,  are  but  two  miles 
apart,  and  bear  the  same  relation  to  the  adjacent  mountain  rnnge.  Tlie 
localities  of  the  Old  River  Bed,  Figs.  4  and  5,  are  five  miles  apart,  and  those 
of  Tooele  Valley,  Figs.  6  and  7,  about  ten  miles  apart. 

The  principal  recent  displacements  of  the  basin  have  been  of  the  nature 
of  broad,  gentle  undidations,  not  aft'ecting  the  horizontality  of  the  shore-lines, 
so  far  as  that  is  distinguishable  by  the  eye.  The  region  including  each 
gi'ou])  of  localities  may  properly  be  assumed  to  have  risen  or  fallen  in  con- 
sequence   of  such    earth  movements    without   important   internal  change; 


ATTEMPTS  TO  EXPLAIN  DISCOKDANCB.  141 

and  this  circumstance  leads  us  to  anticipate  that  the  members  of  each  of 
these  groups  of  embankment  localities  will  be  found  to  correspond  with  each 
other  better  than  with  the  members  of  other  groups  or  with  isolated  locali- 
ties. 

This  expectation  is  realized  in  the  relation  of  the  Bonneville  and  Provo 
sliores.  In  each  of  the  two  Preuss  Valley  localities  tlie  Bonneville-Provo 
interval  is  345  feet.  At  the  two  localities  of  the  Ohl  River  Bed  it  is  400 
feet  and  398  feet.  At  the  two  localities  of  Tooele  Valley  it  is  375  feet  and 
378  feet.  At  the  Point  of  the  mountain,  20  miles  east  of  Tooele  Valley,  it 
is  375  feet.  When,  however,  the  Intermediate  shores  are  considered,  no  cor- 
relation is  found. 

The  harmonious  relations  exhibited  by  the  Bonneville  and  Provo  shore- 
lines at  contiguous  localities  confirm  the  postulate  that  a  general  correlation 
should  be  possible  in  these  localities,  desjiite  the  influence  of  contempora- 
neous displacement,  and  compels  us  to  reject  displacement  as  a  sufficient 
explanation  of  the  discordance  of  the  Intermediate  shore-lines. 

By  these  considerations,  and  by  others  which  it  is  unnecessary  to  de- 
tail, the  writer  was  led  to  abandon  the  hypothesis  of  persistent  water  stages, 
even  though  a  better  was  not  immediately  suggested.  Eventually  another 
was  found,  and  this  is  believed  to  give  a  satisfactory  explanation  of  the  phe- 
nomena.    It  may  be  called  the  hypothesis  of  an  oscillating  water  surface. 

HYPOTHESIS  OF  OSCILLATING  WATER  SURFACE. 

In  order  to  set  foi-th  this  hypothesis,  it  will  be  necessary  to  recur  to 
the  general  theory  of  the  construction  of  shore  emljankments,  page  46, 
and  imagine  how  the  process  would  be  modified  by  the  contemporane- 
ous oscillation  of  the  water  surface.  Let  us  select  some  point  of  the  coast 
where  the  local  conditions  determine  the  deposition  of  shore  drift,  and 
assume  that  a  spit  has  been  formed,  its  crest  being  slightly  higher  than  the 
surface  of  the  water  when  still.  Suppose  now  that  the  height  of  the  water 
surface  is  gradually  increased.  A  portion  or  the  whole  of  the  shore  drift 
contriljuted  by  the  next  stonn  is  deposited  upon  the  top  of  the  embankment, 
tending  to  restore  the  profile  to  its  normal  relation  with  the  still-water  level. 
During  this  restoration  the  growth  of  the  end  of  the  spit  is  retarded,  or  per- 


142  LAKE  BONNEVILLE. 

lia])s  altogether  checked.  If  the  general  rise  of  the  water  is  very  slow,  the 
construction  of  the  embankment  keeps  pace  with  it,  and  the  crest  maintains 
its  nonnal  height,  but  if  the  rise  of  water  is  more  rapid,  the  spit  is  sooner  or 
later  submerged,  so  that  the  stonn  waves  sweep  over  it.  Witli  a  slight  sub- 
mergence, the  course  of  the  shore  cuiTent  is  unchanged,  and  the  waves  still 
break  as  they  reach  the  line  of  the  spit,  so  that  the  conditions  of  littoral 
transportation  are  not  there  abrogated.  A  portion  of  the  force  of  the  waves 
is  expended  on  the  land  inside  the  spit,  but  the  shore  di-ift  is  not  diverted  or 
divided  so  long  as  the  position  of  the  shore  current  remains  luichanged. 
The  growth  of  the  spit  therefore  continues  in  its  submerged  condition,  and 
if  the  water  level  ceases  to  rise,  the  crest  of  the  spit  eventually  emerges  and 
acquires  its  normal  height. 

Assume  now  that  the  rise  of  the  lake  surface,  being  more  rapid  than 
the  growth  of  the  spit,  does  not  cease,  but  continues  indefinitely.  A  time 
must  sooner  or  later  be  reached  when  the  depth  of  water  on  the  submerged 
spit  permits  the  waves  to  pass  over  it  ahnost  unimpeded,  and  at  the  same 
time  penults  the  shore  cm-rent  to  be  deflected  inward.  The  formation  of  a 
new  spit  then  begins  in  a  position  higher  on  the  sloping  side  of  the  basin. 

Now  let  the  tendency  of  the  water  level  be  reversed,  so  that  it  gradu- 
ally falls.  Additions  will  continue  to  be  made  to  the  new  spit  by  the  ac- 
cumulation of  shore  di-ift  on  its  weather  face  and  at  its  end ;  but  sooner 
or  later  the  water  will  reach  a  stage  at  which  the  shore  current  will  be  de- 
flected by  the  lower-lying  spit,  and  at  Avhicli  the  waves  in  sweeping  over 
that  spit  will  be  broken  and  diminished  in  force.  Additions  to  the  upper 
spit  will  then  cease,  and  the  growth  of  the  lower  spit  will  be  renewed. 

If  this  theory  is  well  founded,  there  should  be  produced  at  the  margin 
of  an  oscillating  lake  a  series  of  embankments  separated  by  vertical  inter- 
vals bearing  some  relation  to  the  magnitude  of  the  waves,  and  each  of  these 
should  grow  in  height  every  time  the  oscillating  water  surface  passes  its 
horizon,  either  in  ascending  or  in  descending.  The  rate  of  growth  would 
naturally  be  diff'erent  at  different  points  on  the  margin  of  the  lake ;  and  the 
interval  between  embankments,  being  a  function  of  wave  magnitude,  should 
vary  in  different  regions,  being  greatest  where  cu'cumstances  are  most  favor- 
able for  the  development  of  waves. 


THEORY  OF  OSCILLATING  WATER  SURFACE.  143 

This  relation  between  the  embankment  interval  and  the  local  conditions 
affecting  wave" magnitude  is  so  evident  a  consequence  of  the  theory  that  it 
may  be  used  to  test  its  applicability  to  the  problem  in  question,  and  this 
may  be  further  tested  by  considering  the  phenomena  of  littoral  excavation 
in  connection  with  those  of  littoral  construction.  The  conditions  which 
theoretically  produce  a  rhythm  in  the  process  of  littoral  deposition  have 
no  similar  effect  upon  the  concomitant  erosion.  In  the  regions  of  littoral 
erosion,  the  shore  currents  are  not  deflected  by  circumstances  associated 
with  the  rise  and  fall  of  the  water  level,  and  the  zone  subjected  to  the 
beating  of  the  waves  bears  always  the  same  relation  to  the  still  water  level. 
An  equable  rise  of  the  water  should  therefore  pare  away  the  coast  in  an 
equable  manner;  and  upon  the  theory  of  rhythmic  deposition,  the  Inter- 
mediate embankments  should  not  be  associated  with  sea-cliff's  and  cut- 
ten-aces  of  comparable  magnitude. 

Proceeding  now  to  the  application  of  the  hypothesis  to  the  problem  in 
question,  we  may  premise  that  the  water  level  has  twice  risen  above  the 
Provo  horizon  and  afterward  descended,  one  rise  extending  to  the  Bonne- 
ville shore-line  and  the  other  being  nearly  as  great.  The  space  occupied  by 
the  Intermediate  embankments  has  thus  been  subjected  to  wave  action  at 
least  fom-  times.  These  oscillations  have  been  demonstrated  by  independ- 
ent evidence;  and  it  is  pi'obable  that  there  were  also  numerous  minor  oscil- 
lations. The  conditions  were  therefore  favorable  for  the  production  of  the 
rhj'tluuic  result. 

The  vertical  interspaces  between  the  Intermediate  embankments  yield 
evidence  confirmatory  of  the  hypothesis.  Six  of  the  localities  represented 
in  the  profiles  and  maps  are  suitable  for  comparison.  Among  these  the  local 
conditions  indicate  the  greatest  waves  at  Grantsville  and  Dove  Creek,  and  at 
these  points  the  average  interspaces  between  the  principal  embankments 
are  72  feet  and  75  feet.  The  conditions  are  less  favorable  at  Wellsville  and 
the  Snowplow,  but  it  is  doubtful  which  of  these  two  localities  should  rank 
next  At  Wells\alle  the  average  interspace  is  60  feet.  At  the  Snowplow  it 
is  either  71  feet  or  61  feet,  according  as  an  embankment  of  doubtful  rank  is 
included  or  excluded.  In  Preuss  Valley,  where  there  was  comparatively 
small  scope  for  the  formation  of  waves,  the  average  interspace  is  53  feet. 


144  LAKE  BONNEVILLE. 

Eqiuvlly  liariiionious  i«  tlio  evidence  from  the  iilieiioniena  of  littoral 
excavation.  Take,  for  example,  the  Siiowplow.  The  material  there  aggre- 
gated was  derived  from  a  broad  alluvial  slope,  partly  represented  in  the 
northern  portion  of  tlie  map  (PI.  XIX).  In  this  region  there  is  a  nearly 
continuous  slope  from  the  Provo  terrace  to  the  Bonneville  terrace;  and 
above  the  Boinieville  cliff  there  is  a  continuous  slope  of  undisturbed  allu- 
vium. This  latter  originally  extended  over  the  entire  slope,  including  and 
beyond  the  Provo  horizon,  and  it  can  be  restored  in  imagination  so  as  to 
realize  the  magnitude  of  the  excavation.  From  ten  to  thirty  feet  ai)}Xiar  to 
have  been  removed  from  the  general  surface,  and  this  so  evenly  that  there 
are  only  one  or  two  points  where  the  presence  of  sea-cliffs  can  be  indicated; 
and  even  these  -can  not  readily  be  traced  to  corresponding  embankments. 
The  same  is  true  in  i\  general  way  of  all  localities.  Not  oidy  are  the  In- 
termediate embankments  nowhere  connected  \vith  a  s)'stem  c)f  differentiated 
cliffs  and  ten-aces,  but  it  lias  been  found  impossible,  (wherever  the  attemjjt 
has  lieen  made,)  to  trace  their  horizons  fairly  into  the  region  of  excavation. 
At  the  Snowplow  locality,  the  excavated  alluvium  is  of  such  nature  as  to  be 
easily  modified  by  the  rain  and  it  does  not  preserve  the  minor  details  of  the 
configixration  im])ressed  on  it  by  the  waves;  but  elsewhere,  on  alluvial 
slopes  of  coarser  material,  the  inters])ace  between  the  Bonneville  and  Provo 
cut-terraces  has  been  observed  to  be  occupied  by  a  continuous  s}'stem  of 
naiTow  terraces  and  cliffs,  constituting  a  sort  of  horizontal  striation  of  the 
surface.  At  one  point,  near  Pilot  Peak,  thirty-three  separate  teiTaces  were 
counted,  the  average  interspace  being  less  than  ten  feet. 

The  liy})othesis  receives  additional  support  from  the  structui-e  of  the 
individual  embankments.  The  spit  built  by  the  waves  of  a  lake  with  a  con- 
stant level  should  normally  have  a  certain  simplicity  of  structm'e,  the  prin- 
cipal additions  to  its  mass  being  made  at  the  distal  end,  and  the  deposits 
near  the  crest  having  no  irregularity,  except  that  referable  to  the  disjjarity, 
in  force  and  dij'ection,  of  the  constructive  storms.  A  spit  consti'ucted  by 
the  waves  of  an  oscillating  water  surface  should  theoretically  be  begun  at 
a  relatively  low  level  and  receive  additions  in  the  form  of  superposed 
spits  of  various  altitudes  and  lengths,  some  extending  to  the  end  of  the  mole 
and  others  sto2)ping  short.     The  compound  structure  is  characteristic  of  the 


ACCESSORY  EVIDENCE. 


145 


Intermediate  embankments.  Sectional  exposures  are  indeed  rarely  to  be 
seen;  but  from  many  of  the  embankments  there  project,  either  at  the  distal 
extremity  or  on  the  shoreward  side,  shelves  or  spurs  indicating  the  horizons 
of  the  lower  wave  work  and  testif}'ing  to  the  composite  structure  of  the  mass. 
Fig.  25  gives  an  illustration  of  this,  observed  near  Willow  S2)ring,  west 
of  the  Great  Salt  Lake  Desert.  A  broad  spit  is  characterized  by  a  hook  at 
its  extremity.     A  study  of  its  details  shows  that  the  shore  di-ift,  under  the 


\WM 


Fig.  25. — CompouDd  Hook  of  an  lutermediate  Shore-line  near  Willow  Spring,  Great  Salt  Lake  Desert. 

influence  of  the  dominant  waves,  here  from  the  north  and  northeast,  traveled 
from  a  to  h.  By  less  powerful  waves  from  the  east  and  south  it  was  then 
carried  about  the  end  of  the  embankment  to  the  recurved  point  c,  a  point 
with  a  peculiar  and  notable  outline.  On  the  lee  side  of  the  spit,  at  a  point 
where  the  Avaves  could  have  no  force  after  its  construction,  there  are  tliree 
projecting  tongues  d,  e,  f,  built  of  beach-rolled  gravel  and  closely  resembling 
the  extremity  of  the  point  c.  The  highest  is  twenty  feet  below  the  spit;  the 
others  thirty  and  forty  feet.  They  are  evidently  more  ancient  hooks,  the 
MON  I 10 


146  LAKE  BONNEVILLE. 

appendages  of  similar  but  shorter  and  lower  spits,  which  may  fitly  be  re- 
garded as  progi'essive  stages  of  the  huge  table  ultimately  constructed. 

Finally,  the  single  element  of  order  detected  in  the  accumulated  pro- 
files is  by  this  hypothesis  shown  to  be  consistent  with  the  general  want  of 
order.  The  terrace  (a,  PI.  XXIII)  lying  from  15  to  25  feet  below  the  high- 
est Bomieville  embankment,  was  preserved  because  it  was  the  penultimate 
deposit  of  the  ascending  series,  and  because  the  ultimate  deposit  was  too 
meager  to  mask  it.  The  differentiated  series  of  Bonneville  bars  described 
in  a  preceding  section  shows  that  the  penultimate  water  stage  was  about  20 
feet  below  the  ultimate.  Wlierever  the  penultimate  contribution  to  an  em- 
bankment w^as  made  upon  its  lakeward  face,  it  escaped  concealment  by  the 
final  contribution,  which  was  small  in  amount  and  was  perched  u2)on  the 
top  of  the  same  embankment. 

The  second  hypothesis  is  thus  sustained  at  all  points.  The  Intermedi- 
ate embankments  record  the  wave  action  of  an  oscillating  water  surface. 
Within  this  zone  the  water  level  did  not  long  linger  at  any  one  horizon,  or 
if  it  did,  the  record  of  that  lingering  was  effaced  by  later  action. 

It  follows  as  a  corollary  from  this  discussion  that  cut-ten-aces  with 
their  associated  sea-cliffs  afford  a  more  trustworthy  record  of  persistent 
water  stages  than  do  embankments.  It  is  an  additional  mark  of  persistent 
stages  that  they  afford  coordinated  terraces  and  embankments. 

It  is  impoi'tant  to  note,  however,  that  neither  the  sea-cliff  nor  the  cut 
terrace,  if  observed  alone,  affords  satisfactory  evidence  of  persistent  wave 
action  at  one  horizon.  They  must  be  found  together.  A  slowly  rising 
tide  continually  abandons  the  freshly  cut  teiTace  and  attacks  with  its  waves 
the  freshly  cut  cliff  above  it.  In  this  way  a  cliff  is  carried  before  the  ad- 
vancing water  of  an  oscillating  lake ;  and  when  the  ma.ximum  is  reached 
and  recession  follows,  the  cliff  is  stranded,  so  to  speak,  at  the  upper  limit, 
even  though  the  water  margin  was  retained  there  a  short  time  only.  Sim- 
ilarly, it  is  conceivable  that  a  falling  lake  sm-face  may  carry  before  it  a  cut 
terrace  without  leaving  at  any  horizon  a  sea-cliff  of  comparable  magnitude. 
The  first  of  these  conclusions  has  an  application  in  the  case  of  the  Bonne- 
ville shore-line,  which,  as  already  remarked,  is  characterized  by  the  great 
height  of  its  sea-cliffs,  but  is  inferior  to  the  Provo  shore-line  in  the  widtli 


CIIARACTBRS  GIVEN  BY  STABLE  WATER  LEVEL.  147 

of  its  cut  terraces.  The  considerations  here  adduced  serve  to  complement 
the  ])artial  explanation  of  this  contrast  advanced  on  page  129. 

As  already  intimated,  the  compilation  of  the  Intermediate  embankments 
was  the  result  of  a  series  of  oscillations  of  the  ancient  lake,  whereby  a  zone 
of  wave  action  was  carried  alternately  upward  and  downward  over  the 
slojie.  The  basis  for  this  statement  does  not  lie  in  the  embankments  them- 
selves so  much  as  in  the  associated  lacustrine  and  alluvial  deposits.  It  is 
imquestionably  true  that  the  entire  history  of  oscillation  is  embodied  in  the 
internal  structures  of  the  embankments,  but  these  are  not  exjjosed  for  exam- 
ination, and  the  external  forms  afford  information  for  the  most  part  only  of 
the  Litest  additions. 

It  is  a  curious  fact  that  these  forms  of  embankments  appear  to  have 
been  moulded  by  a  gradually  rising  rather  than  by  a  falling  tide.  The  last 
general  movement  of  the  water  was  of  course  a  recession,  for  the  slopes  are 
now  dry,  but  that  recession  has  left  so  little  trace  above  the  Provo  horizon 
that  we  are  led  to  believe  it  was  far  more  rapid  than  the  preceding  advance. 

This  conclusion  is  as  interesting  as  it  was  unexpected ;  and  it  is  proper 
that  the  evidence  on  which  it  rests  be  presented  somewhat  fully,  especially 
as  it  has  been  assumed  by  several  investigators,  including  myself,  that 
the  several  shore  marks  of  the  series  represent  lingerings  of  the  ancient  lake 
during  a  gradual  recession. 

SUPERPOSITION   OF   EMBANKMENTS. 

The  snowpiow.-  Ill  tlio  first  placc,  there  are  many  superficial  indications  of 
the  overlapping  of  low  embankments  by  high  ones.  If  the  reader  will  turn 
to  the  map  of  the  Snowplow  (PI.  XIX),  he  will  see  that  the  table  lettered  a 
is  not  entirely  supported  by  the  table  b,  but  projects  a  little  on  the  south 
side  so  as  to  rest  partly  upon  the  general  slope  which  is  the  common  founda- 
tion of  both.  (It  is  necessary  to  restore  in  imagination  the  contours  inter- 
rupted by  the  (h-ainage  line  southeast  of  the  letter  a  and  dividing  the 
embankment  it  indicates.)  As  has  already  been  explained,  the  material  of 
the  Snowplow  Avas  derived  from  the  region  fff,  and  was  di-ifted  along  the 
shore  from  southeast  to  northwest.  That  which  composes  the  upper  surface 
of  each  embankment  must  have  been  carried  along  the  southern  edge  of  the 


148  LAKE  BONNEVILLE. 

Snowplow  by  beach  action,  so  that  each  embankment  was,  at  the  time  of  its 
completion,  connected  by  a  continuous  beach  with  the  source  of  supply.  The 
embajikment  h  is  not  so  connected,  for  the  evident  reason  that  its  southern 
edge  has  been  overlapped  b}'  the  latest  addition  to  embankment  a.  If  the 
waves  during  the  recession  of  the  water  had  made  a  contribution  to  the  lower 
embankment,  they  must  either  have  excavated  the  side  of  the  upper  embank- 
ment or  else  have  built  a  platform  around  it,  and  in  either  case  the  slope  from 
the  crest  of  the  upper  to  the  foundation  plain  would  not  have  the  observed 
uniformity  and  steepness.  A  similar  relation  of  parts  shows  that  the  em- 
bankment 1)  was  completed  after  the  embankment  c,  so  that  at  least  three  of 
the  members  of  the  series  received  their  final  moulding  in  ascending  order. 
Reservoir  Butte.-At  Rcscrvoir  Butto  Substantially  the  same  story  is  told,  but 
in  different  language.  The  face  of  the  butte  turned  toward  the  open  lake 
was  rugged  in  the  extreme,  and  the  configuration  of  the  neighboring  bot- 
tom was  irregular,  so  that,  as  the  depth  of  the  water  changed,  the  conditions 
determining  the  transfer  of  shore  drift  and  the  construction  of  em];)ankments 
were  continually  modified.  The  resulting  embankments  were  not  built  into 
a  synnnetric  system  but  Avere  thrown  together  in  an  irregular  and  unique 
group.  By  referring  to  Pis.  XXIV  and  XXV,  where  they  are  represented 
by  vertical  and  horizontal  sketches,^  it  will  ,be  seen  that,  of  those  above  the 
Provo,  the  highest  is  tlic  last  formed,  overlapping  all  the  others.  Number  2 
(tli^y  are  numbered  in  the  order  of  height)  has  no  visible  connection  by 
beach  with  the  north  or  weather  face  of  the  butte,  whence  its  material  was 
derived;  and  its  form  and  relations  show  that  it  could  not  have  been  con- 
structed after  the  completion  of  Number  1.  The  third  and  part  of  the  fourth 
are  in  a  similar  manner  overplaced  by  the  second,  and  were  evidently  earlier 
fomied.  The  fourth  is  however  separable  into  two  parts,  which  may  have 
been  formed  at  different  times;  and  the  outer,  marked  4«  in  the  diagram,  is 
not  so  related  to  No.  2  as  to  demonstrate  the  order  of  sequence.  It  is  hoAvever 
overplaced  by  No.  1.  The  relative  age  of  the  third  and  fourth  is  not  appar- 
ent; but  tho  fifth,  which  lies;  in  a  bay  completely  sheltered  by  the  fourth,  is 
evidently  of  greater  age.     The  sixth  and  eighth  have  no  detenniued  relation 

'  Tho  plat  of  tlicso  eraljankiucnts  Riven  in  PI.  XXV  cinnot  claim  the  accuracy  of  other  maps  of 
embankments.  It  was  sketched  in  the  field  without  the  aid  of  instruments,  and  may  be  very  inaccu- 
rate in  matters  unessential  to  the  discussion  above. 


SUPERPOSITION  OF  EMBANKMENTS.  149 

to  any  other  except  the  first,  which  they  underlie;  and  the  seventh,  which 
projects  from  beneath  the  fourth,  shows  no  direct  relation  with  any  other. 
The  ninth  is  the  Provo,  and  this  proclaims  its  recency  l)y  its  relation  to  the 
first.  Its  table  extends  to  the  north  face  of  the  butte,  and  not  merely  passes 
the  face  of  the  first  or  Bonneville  emljankment  but  is  in  part  carved  from  it. 
The  Provo  waves  encroached  also  upon  the  eighth  embankment.  These 
relations  may  be  tabulated  in  the  following  form,  in  which  the  word  "ante" 
should  be  construed  to  mean  completed  at  an  earlier  date  than. 


^  \  ante  2 
5  ante  4  \ 

-  >  ante  4a 


•  ante  1  ante  9 


stockton.-Another  unique  aggregate  of  embankments  is  equally  instruct- 
ive. Previous  to  the  rise  of  the  lake,  the  drainage  of  Rush  Valley  was  tribu- 
tary to  that  of  Tooele  Valley,  the  connecting  parts  having  a  continuous 
descent  from  south  to  north,  and  an  ample  channel,  of  which  a  portion  is  yet 
clearly  to  be  seen.  At  the  point  of  greatest  constriction  between  the  two 
valleys,  where  the  Bonneville  strait  had  a  width  of  only  8,000  feet,  the  bot- 
tom of  the  channel  ran  about  350  feet  below  the  level  afterward  marked  by 
the  Bonneville  shore.  At  all  high  stages  of  the  lake  the  strait  received  a  large 
quantity  of  shore  diift  from  the  northeast,  and  a  series  of  curved  bars  were 
thrown  across  it.  These  bars  have  a  total  width  of  5,000  feet,  and  partially 
overlap  each  other,  so  as  to  constitute  a  single  earthwork  of  colossal  propor- 
tions. Whenever  the  water  surface  fell  below  the  highest  completed  bar,  the 
Rush  Valley  bay  was  completely  severed  from  the  main  body,  and  became 
a  lake  by  itself  This  lake  was  so  small  that  its  waves  were  comparatively 
powerless;  and,  although  traces  of  their  work  can  be  discovered,  they  did 
not  materially  influence  the  configuration  of  the  earthwork.  The  locality  is 
exhibited  in  the  foreground  of  the  view  in  PI.  IX  and  in  the  map  and  2;)ro- 
file  of  PI.  XX.  If  the  reader  will  refer  to  the  latter  plate  and  give  attention 
to  the  profile  in  connection  with  the  map,  he  will  see  that  the  bars  rise  in 
consecutive  order  from  a  to  g,  and  that  each  has  a  curved  axis  with  concavity 
toward  the  north.     This  curvature,  which  is  characteristic  of  bay  bars  in  gen- 


150  LAKE  BONNEVILLE. 

eral,  shows  that  the  waves  concerned  in  their  production  came  from  the  north. 
It  is  evident  that  after  the  bar  b  was  constructed,  the  bar  a  was  protected 
from  all  further  wave  action,  a  was  therefore  completed  before  b  was  built; 
and  in  general  the  order  of  construction  could  not  have  been  other  than  the 
order  of  the  letters, — the  lowest  bar  a  being  the  first,  and  the  highest  bar  g, 
the  last.  The  order  of  construction  was  therefore  from  low  to  high.  It  is 
to  be  noted  that  this  order  is  demonstrated  only  for  the  visible  or  superficial 
portions  of  the  earthwork.  There  may  be  beneath  the  bar  ff,  for  example, 
a  deeply  buried  series  of  bars  lower  than  a,  and  either  younger  or  older;  and 
so  of  any  other  of  the  higher  bars.  We  have  no  reason  to  believe  that  the 
whole  history  is  embodied  in  the  visible  phenomena. 

The  bar  g  diff"ers  from  the  others  in  that  it  is  not  unifoiTQ  in  height 
thi'oughout  its  length.  The  lowest  point  of  its  crest  is  approximately  in  the 
position  occupied  by  the  letter;  and  from  this  there  is  an  ascent  of  about  30 
feet  toward  either  shore.  At  the  Bonneville  stage  the  strait  was  not  closed 
by  a  bar,  but  the  shore  drift  was  built  into  spits.  That  at  the  west  is  short 
and  has  the  fonn  of  a  hook.  It  is  crested  from  end  to  end  by  a  slender  ridge, 
built  at  the  cuhninating  water  stage.  The  eastern  is  straight  and  broad  and 
6,000  feet  in  length.  Its  proximal  end  bears  two  small  spits,  referable  to  the 
cuhninating  stage  of  the  water;  and  its  distal  end  evidently  overlajis  the 
lower  members  of  the  compound  earthwork.  So  far  as  outward  api)earance 
goes,  this  is  purely  the  product  of  shore  action  at  the  Bonneville  stage ;  but 
it  is  possible  that  similar  spits  were  formed  at  lower  stages,  so  as  to  consti- 
tute a  foundation  for  the  Bonneville  spit. 

One  of  the  most  striking  features  of  the  series  of  bars  is  the  paucity  of 
wave  marks  upon  the  northern  face.  There  is  a  diminutive  bar,  character- 
ized by  an  abundance  of  tufa,  imposed  on  the  face  of  the  gi-eat  bar  g  four 
feet  below  its  crest ;  and  twelve  feet  lower  a  wave-cut  terrace  is  barely  per- 
ceptible. These  may  record  an  oscillation  of  the  water  after  the  comple- 
tion of  the  great  bar  and  before  it  rose  to  the  Bonneville  shore ;  or  they 
may  have  been  produced  by  the  receding  water  after  the  highest  level  had 
been  touched.  In  any  event,  the  final  recession  must  have  brought  every 
foot  of  the  northern  slope  of  the  earthwork  within  reach  of  the  waves,  and 


SEQUENCE  OF  BARS  AT  STOCKTON.  151 

the  surviving  continuity  of  the  slojie  testifies  to  the  rapidity  of  the  reces- 
sion. The  conditions  for  wave  work  were  unchanged.  The  alluvial  slopes 
which  had  furnished  the  gravel  for  the  several  embankments,  still  offered  an 
inexhaustible  supply,  and  the  same  currents  and  waves  must  have  been  set 
in  motion  by  the  storm  winds ;  but  the  lake  seems  not  to  have  tarried  long 
enough  at  any  one  level  to  add  a  terrace  to  the  structure. 

Another  evidence  of  the  rapidity  of  the  final  descent  of  the  waters  is 
found  in  the  fixilure  of  the  waves  at  any  of  the  Intermediate  horizons  to  un- 
dercut the  embankments  constructed  at  the  higher  stages.  If  the  water 
tan-ies  long  at  one  level,  the  changes  it  effects  in  the  form  of  the  shore 
finally  modify  the  currents  so  as  to  shift  slowly  the  districts  of  erosion  and 
of  construction.  Spots  that  were  at  first  excavated  are  afterward  made  to 
receive  deposits,  and  portions  of  the  original  deposit  are  afterward  removed. 
Instances  are  known  in  which  the  Provo  waves  have  pushed  their  excava- 
tion to  the  heart  of  the  Intermediate  embankments,  so  as  to  undercut  even 
the  highest  members ;  and  there  are  few  localities  of  great  wave  action 
which  do  not  exhibit  more  or  less  encroachment ;  but  there  is  no  evidence 
that  the  waves  of  any  Intermediate  stage  have  seriously  impaired  any  higher 
embanlanent.  There  is  a  narrow  wave-cut  terrace  on  the  north  face  of  the 
Stockton  earthwork ;  two  lines  are  engraved  on  the  points  of  Intermediate 
terraces  in  the  Snowplow;  and  there  is  possibly  a  similar  occurrence  in 
Preuss  Valley  ;  but  no  locality  gives  evidence  of  long-continued  action. 

Blacksmith  Fork.-Thc  uudercuttiug  of  the  Provo  shore  has  in  two  places 
exposed  instructive  sections  of  the  Intermediate  embankments.  At  the 
south  end  of  Cache  Valley,  close  to  the  point  where  Blacksmith  Fork 
issues  from  the  mountain,  there  is  a  section,  nearly  300  feet  in  height,  show- 
ing a  face  of  clean  gravel,  which  has  slidden  down  so  as  to  cover  the  entire 
surface — if,  indeed,  it  does  not  constitute  the  entire  mass.  At  four  horizons 
this  is  barred  across  by  level  lines  of  cemented  gravel  marking  successive 
positions  of  the  upper  surface  of  the  mass  as  it  was  piled. 

Dove  Creek.- A  siuiilar  cscarpment  of  gravel  is  exposed  on  the  soiith  face 
of  the  Dove  Creek  group  of  embankments  (see  profile  diagram  on  PI. 
XXII.),  and  a  similar  series  of  parallel  lines  can  be  traced  across  it.  They 
are  best  seen  from  a  distance,  and  on  close  examination  prove  to  consist 


152  LAKE  BONNEVILLE. 

merely  of  a  scattering  growth  of  bushes.  There  is  no  visible  variation  in 
the  character  of  the  gravel,  but  the  position  of  tlie  bushes  is  doubtless  di.'- 
termined  by  the  existence  beneath  the  surface  of  relatively  impervious  strata. 
Whatever  the  nature  of  these  strata,  they  are  elements  of  structnr(i  iind 
demonstrate  the  growth  of  the  series  of  embankments  from  the  base  iipward. 
The  featm-e  especially  interesting  is  the  relation  of  the  section  to  the  unim- 
paired eastern  face  of  the  embankment  group.  Each  line  ttf  division  is  the 
continuation  of  the  iipper  plane  of  a  terrace,  so  that  the  terraces  are  shown 
to  be  units  of  stratiiication.  The  evidence  from  external  foiTu  is  thus  con- 
nected with  that  from  internal  structure ;  and  the  general  conclusion  in 
regard  to  the  succession  of  the  Intermediate  terraces  is  strengthened. 

Here,  as  in  the  other  localities  mentioned,  it  is  necessary  to  guard 
against  the  impression  that  the  entire  history  of  the  lake  during  the  forma- 
tion of  the  Intermediate  shore-lines  is  revealed  l)y  what  can  be  seen  of  the 
embankments.  These  structure  lines  do  not  extend  through  the  entire  mass, 
and  no  other  lines  replace  them.  Those  portions  of  the  general  mass  of 
detritus  which  lie  next  to  the  original  hill  slope  may  have  been  accumulated 
by  rising  or  falling  waters,  or,  for  aught  we  know,  by  a  surface  subjected 
to  many  oscillations.  In  the  case  of  the  Snowplow,  all  that  we  can  predi- 
cate is  that  the  latest  additions  to  the  mass  were  made  in  ascending  order. 
With  reference  to  the  Stockton  eartliAvork,  we  know  only  that,  of  a  certain 
series  of  visible  bar  crests,  the  order  of  height  is  also  the  order  of  date.  It 
is  not  only  possible  but  even  probable  that  the  series  is  discontinuous,  hav- 
ing been  interrupted  by  epochs  when  the  water  was  too  low  to  add  to  the 
accumulations  at  this  point. 

Double  Series  in  Preuss  Valley.-But,  Avllilc  it  WOuld  liave  bcCU  iuipOSsiblc  tO  gaiu 

a  knowledge  of  the  repetitive  movements  of  the  lake  surface  from  shore 
phenomena  alone,  they  nevertheless  serve  to  supplement  the  information 
afforded  by  the  lake  sediments.  Having  learned  from  the  sediments,  as 
will  be  explained  in  anotlier  place,  that  the  wati'r  rose  at  least  Uvice  from 
the  lower  to  the  higher  parts  of  the  basin,  besides  undergoing  many,  minor 
oscillations,  it  was  not  difficult  to  see  that  certain  of  the  shore  embankments 
were  referable  to  an  earlier  flood  than  certain  others.  The  most  important 
locality  is  illustrated  by  the  map  and  sketch  of  PI.  XVI,  and  shows  a  series 


DOUBLE  RECORD  IN  PREUSS  VALLEY.  153 

of  curved  bars  (h  hh  hj,  overlapped  by  a  series  of  spit-like  embankments 
massed  together  into  a  few  sloping  terraces  (t  t  t).  The  source  of  the  shore 
drift  was  at  the  north,  and  the  beaches  which  conveyed  it  to  tlio  curved 
bars  are  hidden  b)'  the  later  erabaidcments.  It  would  be  impossible  for  the 
bars  to  originate  under  the  lee  of  the  spits.  Moreover,  the  spits  everywhere 
exhibit  their  gravelly  constitution,  but  the  curved  bars  are  half  buried  by 
lake  deposits. 

DELTAS. 

The  earliest  allusion  to  the  deltas  of  the  ancient  lake  is  by  Bradley, 
who  remarks  tliat  the  lake  terraces  "  are  much  more  numerous  near  tlie 
mouths  of  the  streams,  where  the  stream-currents  have  distril)uted  their 
sediment,  when  the  lake  waters  were  at  these  higher  levels";^  but  the 
first  clear  discrimination  of  the  deltas  from  other  terraces  was  by  Howell, 
whose  observations  were  made  only  a  few  months  later.  Speaking  of  the 
horizon  of  the  Provo  shoi'e-line,  he  says  : — "When  the  old  lake  stood  at  this 
level,  the  detritus  brought  down  liy  the  Provo  River  formed  a  delta,  cov- 
ering at  least  twenty  thousand  acres.  Another  delta  was  formed  at  this  time 
at  the  mouth  of  Spanish  Fork  Canyon,  in  the  same  valley,  which  covered 
an  area  of  eight  thousand  or  ten  thousand  acres."" 

It  was  the  magnitude  of  the  former  of  these  deltas  that  led  Plowell  to 
suggest  the  application  of  the  local  name  Provo  to  the  shore-line  at  that  level. 
It  is  now  known  not  only  that  all  of  the  more  notable  deltas  of  the  basin 
appertain  to  the  same  shore-line,  but  that  the  delta  built  by  each  stream  at 
that  level  equals  or  exceeds  in  mass  the  aggregate  of  its  deltas  at  all  other 
levels.  At  higher  levels  such  accumulations  are  exceedingly  rare  ;  and  at 
lower  they  appear  to  have  derived  their  material  largely  from  the  partial 
destruction  of  the  Provo  deltas. 

In  attempting  to  translate  these  facts  into  terms  of  geologic  history,  the 
first  impression  is  that  the  lake  surface  was  held  at  the  Provo  level  during 
more  than  half  the  period  of  its  existence,  but  a  fuller  consideration  shows 
that  this  conclusion  is  not  warranted.  The  degradation  of  the  uplands  and 
the  offscouring  of  the  rivers  are  doubtless  sufficiently  uniform  in  rate  to 

'Frank  H.  Bradley:     Geol.  Surv.  of  Terr.,  Ann.  Rept.  1872,  p.  192. 

2  Edwin  E.  Howell :     Geol.  Surv.  West  of  100th  Meridian,  vol.  3,  p.  250. 


154  LAKE  BONNEVILLE. 

afford  the  basis  for  a  time  scale,  but  there  are  important  modifying  condi- 
tions given  by  tlie  relations  of  the  oscillating  lake  surface  to  the  configura- 
tion of  the  stream  valleys. 

In  the  discussion  of  shore  processes,  it  was  pointed  out  that  the  detritus 
brought  to  a  lake  by  a  small  stream  is  absorbed  by  the  shore  drift,  while 
that  brought  by  a  large  one  overwhehns  the  shore  di-ift  and  records  its  acces- 
sion by  a  delta.  The  codeterminauts  are,  on  the  one  hand,  the  magnitude 
of  the  lake  and  the  consequent  force  of  the  waves,  and  on  the  other,  the 
volume  of  the  stream's  load  of  detritus.  In  the  case  of  Lake  Bonneville, 
the  number  of  streams  competent  to  project  deltas  from  the  shores  of  the 
open  lake  or  of  the  larger  bays,  was  small;  and  it  is  believed  that  all  of 
their  ancient  mouths  have  been  examined.  With  very  few  exceptions,  they 
enter  the  lake  basin  through  mountain  gorges  so  deeply  eroded  before  the 
lake  epoch  that  the  rising  water  set  back  into  them,  forming  naiTOw  estua- 
ries. Knowing  as  we  do  from  the  study  of  the  Intermediate  shore  embank- 
ments that  the  water  rose  slowly  as  it  apjijroached  the  highest  level,  we  can 
not  doubt  tliat  the  stream  di-ift  was  contemporaneously  accumulated  into  a 
series  of  deltas  within  the  mountain  gorges.  Afterward,  when  the  water 
fell  rapidly  to  the  Provo  level  and  there  rested,  the  streams  attacked  the 
deltas  in  the  defiles  and  carried  their  substance  farther  lakeward  to  form 
new  structiires.  These  new  structures  began  for  the  most  part  within  the 
walls  of  the  defiles,  and  were  progressively  built  outward  until  they  pro- 
truded into  the  open  lake,  where  space  permitted  them  to  develop  into  typ- 
ical fan-shaped  deltas.  'The  material  furnished  by  the  older  deltas  in  the 
defiles  was  close  at  hand,  and  in  a  condition  peculiarly  favorable  for 
removal.  Not  only  was  it  uncemented,  but  it  was  confined  to  the  very 
courses  of  the  streams,  so  that  it  could  not  escape  their  action.  It  must  have 
been  rolled  to  its  new  position  hi  an  exceedingly  short  time ;  and  we  need 
not  be  surprised  that  the  traces  of  its  original  forms  are  nearl}-  ol)literated. 
The  rapidity  with  wliich  delta  alluvia  are  torn  up  and  carried  away  bv  run- 
ning water  finds  al)undant  illustration  at  the  present  time  in  the  irrigation 
districts  of  Utah.  Wherever  the  water  of  a  canal  breaks  through  its  bank, 
or  is  neglected  and  suifered  to  discharge  unguided  down  a  delta  slope,  it 
quickly  erodes  a  canada  of  formidable  proportions. 


DELTAS  OF  LAKE  BONNEVILLE.  155 

Deltas  associated  with  the  Provo  shore  are  thus  composed  not  merely 
of  tlie  contemporaneous  outscour  of  the  catcliment  basins  of  their  several 
streams,  but  of  the  detritus  antecedently  accumulated  in  the  estuaries  dur- 
ing the  higher  water  stages ;  and,  so  far  as  they  afford  a  time  ratio,  they 
represent  the  entire  period  during  which  the  water  stood  at  and  above  the 
Provo  horizon.  There  are,  however,  a  few  exceptional  localities  where  the 
Bonneville  estuaries  were  so  small  and  shallow  that  the  stream  drift  not 
merely  filled  them  but  threw  out  semicircular  capes  into  the  Bonneville 
lake ;  and  in  such  cases  it  is  possible  to  make  a  comparison  between  the 
magnitude  of  the  structures  pertaining  severally  to  the  Bonneville  and 
Provo  epochs. 

American  Fork  Deita.-Tlie  best  locaHty  for  such  obscrvation  is  on  a  tributary 
of  Utah  Lake  known  as  the  American  Fork,  and  this  was  carefully  exam- 
ined for  me  by  Mr.  Russell.  The  Bonneville  delta  there  displayed  has  a 
radius  of  nearly  5,000  feet,  and  a  height  at  its  outer  margin  of  120  feet.  It 
is  bisected  by  the  creek,  and  is  thus  cut  nearly  or  quite  to  its  base.  The 
walls  of  the  channel  exhibit  a  section  of  the  deposit,  showing  it  to  consist 
chiefly  of  rounded  gravel,  with  some  intermingled  sand.  The  gravel,  being 
uncemented,  will  not  hold  an  escarpment,  but  flows  down  in  the  fonn  of  a 
talus  wherever  it  is  excavated  by  the  stream,  thus  masking  the  greater  part 
of  the  stiixcture.  There  is,  however,  some  indication  of  horizontal  bedding. 
The  outer  margin  of  the  terrace  is  fortunately  more  communicative.  Around 
three-fourths  of  its  periphery  there  runs  a  narrow  shelf  half-way  down  the 
steep  face ;  and  the  details  of  this  shelf  show  that  it  is  the  protruding  edge 
of  an  older  and  lower  delta  terrace,  furnishing  the  foundation  for  the 
upper.  At  some  points  lake  beds  were  found  intercalated  with  the  alluvial 
gravels,  but  they  appear  to  be  local  deposits  and  not  continuous  sheets 
traversing  the  whole  body.  The  most  complete  local  section  has  been  intro- 
duced into  the  accompanying  diagram,  and  presents  the  following  sequence : 

6.  Well  rounded  gravel,  forming  the  top  of  the  upper  terrace;  20  feet. 
5.  Lake  beds;  laminated  clays  with  .dmnicoJa;  30  feet. 
4.  Well  rounded  gravel ;  15  feet. 

3.  Well  rounded  gravel  cemented  at  the  top  by  calcareous  tufa ;  constituting  a  bench  on  the 
face  of  the  terrace  ;  20  feet. 

2.  Well  rounded  gravel ;  constituting  locally  a  distinct  bench  ;  25  feet. 
1.  Lake  beds,  to  foot  of  slope,  10  feet. 


156 


LAKE  BONNEVILLE. 


The  continuity  of  the  gravels  3  and  G  throughout  the  whole  mass  is 
shown  by  their  relations  to  tlie  topography.  Each  marks  a  water  stage 
during  which  a  broad  delta  was  built  in  the  lake.  The  beds  numbered  2 
and  4  are  identical  in  charactcu-,  and  may  be  salients  of  similar  deltas,  here 
locally  brought  to  light  and  elsewliere  comjdetely  buried;  or  they  may  be 
merely  local  masses  of  alluvium,  marking  the  i)Ositions  held  ]jy  the  creek 
during  temporary  fluctuations  of  the  lake  level. 

At  another  point  of  the  profile,  a  less  complete  section  was  observed, 
exhibiting  a  rapid  alternation  of  gravels  and  clays  in  the  lower  part  of  the 
mass,  and  at  a  few  other  points  short  tongues  of  gravel  were  seen  to  project 
from  the  table  at  various  levels. 


Flu.  :i*i.— Ucuoralizud  soctiou  or  Deltas  at  the  mouth  of  American  Fork  Canyon,  Utah.    By  I.  C.  Russell.    Uonzontal 
scale,  4,500  feet  =  1  inch.    Vertical  scale,  300  feet  =  1  inch. 

These  indications  of  complexity  of  structure  accord  well  with  such  con- 
ceptions of  the  oscillation  of  the  lake  at  these  stages  as  we  have  derived  from 
the  phenomena  of  the  Intermediate  embankments.  If  its  surface  was  incon- 
stant, rising  and  falling,  like  the  surface  of  Great  Salt  Lake,  with  an  irregu- 
lar rhythm,  all  processes  of  deposition  at  the  mouth  of  a  stream  would  be 
successively  interrapted,  and  any  detailed  section  should  show  e^adence  of 
alternation.  A  rising  tide  would  induce  the  formation  of  a  delta  far  up  the 
slope  and  give  opportunity  for  the  accumulation  of  lake  beds  farther  do\\n. 
A  falling  tide  would  cause  the  stream  to  deepen  its  channel  by  the  partial 
erosion  of  the  incipient  delta,  and  perhaps  of  lake  beds  also,' and  would 
cause  a  local  deposit  of  gravel  at  some  lower  level.     A  reascent  would  re- 


OLD  DELTAS  OF  AMERICAN  FORK.  157 

pair  the  breach  in  tlie  delta,  and  a  redescent  might  conduct  the  stream  drift 
in  some  new  direction.  The  same  oscillations  would  carry  the  waves  to  all 
parts  of  the  surface  and  enable  them  to  work  over  the  detritus,  adding  their 
tribute  to  the  general  confusion. 

Assuming  that  the  water  did  actually  oscillate  to  and  fro  during  the 
compilation  of  the  delta,  it  is  manifestly  impossible  to  trace  in  detail  and  in 
true  sequence  the  processes  which  make  up  its  history.  The  most  that  can 
be  affirmed  is  that  a  definite  stage  is  marked  at  the  liorizon  of  Bed  No.  3, 
where  the  water  stood  long  enough  to  complete  a  well  developed  delta  ter- 
race, and  that  a  similar  definite  stage  is  marked  by  Bed  No.  6,  which  is  a 
continuous  delta  sheet  almost  coincident  in  area  with  the  one  below.  The 
lake  level  rejiresented  by  this  higl  ;st  delta  falls  within  the  range  to  which 
the  Bonneville  shore-line  pertains,  but  was  not  the  absolute  maximum.  It 
is  probable  that  the  latter  is  represented  by  a  shoal-water  bar  which  crosses 
the  south  part  of  the  delta  with  a  crest  about  20  feet  higher  than  the  delta 
margin. 

The  locality  thus  exhibits  at  least  three  ancient  deltas,  of  which  the 
order  of  position  is : — 

Bonneville  delta;  capped  by  Bed  No.  6. 
Intel-mediate  delta;  capped  by  Bed  No.  3. 
Provo  delta. 

In  the  order  of  time  the  Intermediate  comes  first  and  the  Provo  last. 
The  Intei-mediate  was  built;  the  Bonneville  was  spread  over  its  back,  but 
failed  to  cover  it  coniijletely;  the  lake  fell,  and  the  two  were  eroded  by  the 
creek,  the  Provo  being  formed  at  the  same  time.  Finally  tlie  Provo  shore 
also  Avas  abandoned  by  the  lake  water,  which  receded  to  its  i)resent  position 
in  Utah  Lake.  The  creek  has  opened  a  broad  passage  through  the  Provo 
delta,  cutting  it  at  the  outer  margin  to  its  base,  and  is  engaged  in  building 
a  modern  delta  in  the  modern  lake.  The  apex  of  this  delta  lies  within  the 
channel  through  the  Provo  delta,  and  is  continuous  with  the  flood  plain  of 
the  upper  course  of  the  stx-eam. 

The  modern  stream  Ijed  has  a  more  rapid  fall  than  the  ancient,  as  will 
be  seen  by  comparing  the  profiles  of  the  modern  flood  plain  and  the  Provo 
delta,  as  exhibited  in  the  diagram.     This  is  due  chiefly  to  the  lowering  of 


158  LAKE  BONNEVILLE. 

the  stream's  mouth;  but  it  is  also  due  in  part  to  the  elevation  of  its  point  of 
issue  from  the  mountain.  A  recent  fault  has  lifted  the  movmtaiii  witli  refer- 
ence to  the  valley  through  a  space  of  70  feet. 

Tliere  is  perhaps  no  locality  more  favorable  than  this  for  the  estima- 
tion of  the  time  ratios  of  the  higher  lake  levels,  but  even  here  it  is  f;n-  from 
satisfactory.  The  Provo  delta  of  American  Fork  coalesces  with  the  con- 
temporaneous delta  formed  by  the  next  creek  to  the  north  in  such  way  that 
it  is  impracticable  to  di-aw  a  line  of  separation;  and  there  is  no  record  of 
the  tribute  made  by  American  Fork  during  the  rising  of  the  lake  until 
it  reached  a  level  barely  100  feet  below  the  Boimeville.  Nevertheless,  it  is 
instructive  to  make  such  comparisons  as  the  circumstances  })ermit,  and  Mr. 
Russell's  field  notes  have  enabled  him  to  compute  approximately  the  vol- 
umes of  alluviiun  accumulated  at  the  different  levels. 

MillioDH  of 
cubic  yards 

Voluiuo  of  Bonneville  aud  Intermediate  deltas  before  erosion  by  the  creek 330 

Volume  of  alluvium  conteniporaueously  deposited  in  mouth  of  bed-rock  canyon 5 

Total  volume  of  gravel  furnished  by  American  Fork  while  the  lake  leA-el  was  within 

100  feet  of  the  highest  stage 335 

Volume  of  Provo  delta  of  American  Fork  (the  separation  from  delta  of  Dry  Creek  being  arbi- 
trarily made) - 400 

Deduct  gravel  derived  from  Bonneville  and  Intermediate  deltas 28 

Deduct  gravel  derived  from  mouth  of  bed-rock  canyon 5 

Total  volume  of  gravel  furnished  by  American  Fork  while  the  lake  stood  at  the  Provo 

level »67 

If  these  quantities  were  well  ascertained,  instead  of  being  rudely  esti- 
mated, they  would  show  the  gravel  tribute  of  the  stream  to  have  been  sliglith- 
greater  during  the  Provo  epoch  than  during  the  last  100  feet  of  the  antece- 
dent rising,  and  would  warrant  the  inference  that  the  time  during  which  the 
lake  level  lingered  within  100  feet  of  its  highest  mark  was  slighth-  exceeded 
l)y  the  duration  of  the  Provo  stage;  and,  after  all  allowance  has  been  made 
for  imj)ei'fection  of  data,  there  remains  a  presumption  that  the  Provo  epocli 
is  comparable  in  dui-ation  with  the  epoch  or  epochs  recorded  by  the  upper 
deltas. 

Mr.  Russell  has  computed  also  the  volume  of  gravel  furnislied  Ijy  the 
creek  after  the  completion  of  the  Intermediate  delta,  finding  it  to  be  153 


■      TIME  RATIOS.  159 

million  yards.  This  represents  the  tribute  of  the  creek  for  all  lake  changes 
within  50  feet  of  the  maximum,  and  includes  the  Bonneville  tribute.  Its 
ratio  to  the  estimated  Provo  tribute  is  as  5  to  12.  It  is  perhaps  fair  to  as- 
sume that  one-half  of  this  mass  pertains  to  the  Bonneville  shore  proper; 
and  on  that  assumption  the  indicated  ratio  of  the  epochs  of  the  Bonneville 
and  Provo  shores  is  as  1  to  5.  Quantitatively,  this  estimate  has  not  a  high 
value,  but  qualitatively  it  serves  to  confirm  the  impression  derived  from 
the  wave  work  of  the  Bonneville  and  Provo  shores. 

It  is  worthy  of  note  that  the  only  halt  of  the  lake  surface  which  here 
finds  record  between  the  Provo  and  Bonneville  horizons,  was  a  halt  of  the 
advance  and  not  of  the  retreat.  The  Intermediate  delta  is  unmistakably 
older  than  the  Bonneville;  and  there  is  none  younger  except  the  Provo. 
There  was  of  course  no  cessation  of  stream  action  while  the  water  of  the 
lake  was  falling  from  tlie  high  mark  to  the  low.  The  creek  must  have  be- 
gun the  erosion  of  the  Bonneville  delta  as  soon  as  its  point  of  discharge 
was  at  all  lowered  by  the  recession  of  the  lake;  and  the  product  of  that 
erosion  must  have  been  deposited  at  the  mouth  of  the  creek  in  the  form  of 
a  delta  or  group  of  deltas,  but  the  eroded  channel  was  so  narrow  and  the 
resulting  deposits  were  of  so  small  bulk  that  later  action  destroyed  them. 
Wliile  the  Provo  delta  was  being  built  the  channel  through  the  Bonneville 
was  enlarged  nearly  to  its  present  dimensions,  and  no  stream  terrace  sur- 
vives to  mark  the  earlier  stages  of  its  excavation.  In  the  same  period  the 
creek  tore  down  and  removed  whatever  deltas  it  may  have  built  at  the  shore 
of  the  receding  lake.  If  the  lake  had  halted  and  lingered  by  the  way,  the 
creek  would  have  been  able  to  carve  a  broad  flood  plain  and  spread  a  broad 
delta,  some  vestiges  of  which  would  survive ;  and  we  can  legitimately  infer 
from  their  absence  that  the  recession  of  the  lake  was  rapid  and  without  in- 
terruption until  the  Provo  level  was  reached. 

When  the  lake  afterward  shrank  away  from  the  Provo  delta,  its  move- 
ment was  less  precipitate.  The  channel  then  opened  by  the  creek  has  a 
maximum  depth  of  only  70  feet,  but  five  separate  stream  terraces,  cut  from 
its  right  wall,  record  the  hesitation  of  the  water  as  it  fell. 

Logan  Delta.- One  of  tlio  most  beautiful  and  symmetrical  of  all  the  deltas 
is  that  constructed  by  Logan  River  at  the  Provo  stage  of  the  lake.     The 


160  LAKE  BONNEVILLE. 

river  enters  Cache  Valley  from  the  east,  debouching  from  a  bold  mountain 
front  through  which  it  has  eroded  a  narrow  V-form  canyon.  At  the  mouth 
of  the  canyon  the  Bonneville  shore-line  is  engraved  on  the  rock  nearly  five 
hundi-ed  feet  above  the  river,  and  the  grade  of  the  river  bed  indicates  that 
when  the  line  was  cut  the  lake  water  set  l)ack  into  the  nan-ow  way  a  dis- 
tance of  about  four  miles.  There  are  are  some  slight  traces  of  gravel  ac- 
cumulations within  the  canyon,  but  it  probably  was  only  partially  filled, 
and  certainly  no  delta  was  foi-med  in  the  lake  at  the  Bonneville  level.  If 
any  estuary  existed  at  the  Provo  stage  it  was  small  and  quickly  filled  with 
alluvium.  The  apex  of  the  Provo  delta  is  at  the  mouth  of  the  canyon,  and 
about  this  point  as  a  center  the  margin  describes  an  arc  of  about  130  degi'ees 
with  a  radius  of  8,000  feet  (see  map  and  profile  of  PI.  XXVI).  Tlie  upper 
surface  is  visibly  and  distinctly  conical,  having  a  radial  slope  in  all  direc- 
tions from  the  apex  of  55  feet  to  the  mile,  or  three-fifths  of  a  degree  from 
the  horizontal.  At  the  margin  this  gentle  inclination  is  abruptly  exchanged 
for  a  declivity  of  about  20  degrees.  At  the  north  the  terrace  joins  and  coa- 
lesces with  a  similar  and  contemporaneous  but  smaller  terrace  pertaining  to 
what  is  now  a  small  creek.  The  marginal  height  of  tlie  terrace  is  about  125 
feet.  During  its  construction  the  river  occupied  every  part  of  its  surface  in 
turn,  and  when  the  construction  work  was  brought  to  an  end  l)v  the  lower- 
ing of  the  lake,  and  the  excavation  of  a  channel  was  begun  liy  the  ri\er, 
the  position  of  that  channel  was  determined  by  the  chance  position  (tf  the 
shifting  stream.  It  is  not  medial,  but  bears  so  far  to  the  south  tliat  the 
northern  remnant  of  the  delta  is  two  or  three  times  greater  than  the  southern. 
As  soon  as  the  erosion  of  the  Provo  delta  conunenced,  the  1)uilding  of 
a  new  delta  Avas  begun  at  a  lower  level,  and  the  apex  of  the  new  delta  was 
at  the  mouth  of  the  channel  through  the  Provo.  With  the  progressiA'e  low- 
ering of  the  lake,  yet  other  and  lower  deltas  were  built,  the  construction  of 
each  being  accompanied  by  the  partial  or  complete'  destruction  (»!'  tliose 
above  it ;  and  this  continued  luitil  the  desiccation  of  the  valley.  For  two 
miles  below  the  Provo  delta,  each  Ijiiiik  of  tlie  modern  river  is  lined  by  the 
remnants  of  these  old  deposits,  four  or  five  lying  on  each  side.  One  of  the 
most  conspicuous  has  been  selected  as  the  site  of  the  Logan  Temple,  and 
two  lower  benches  are  occupied  by  the  town  of  Logan.     A  glance  at  the 


I- S. GEOLOGICAL    SURVEY 


LAKE  BONNEVILLE     FLXXVI 


MAP    OF  THE 

D  1",  I.T  A  S 

1.11  mc-a    111 

AKE    nONNKVIlJ.I': 

bv    llii- 

LOC.AN  KIVEK 

Rv  ^V'^    D   Joliiisoii  . 


''WiJii'flfP"'''"'' 


Pro  111  e 
Vertit'ol   Sivii-   ilouOlc   the    Borixonin.1 


ZS-  feet     Cyntmu's . 


Temple 


Jul,i,«  Hicn  .vi'o.l.th 


Dravni  by  (*  Tliompiji 


OLD  DELTAS  OF  LOGAN  RIVER.  161 

map  will  show  their  arrangement  l)etter  than  any  description.  The  river  has 
developed  so  broad  a  flood  plain  that  half  their  mass  has  disappearetl,  and 
the  dissevered  remnants  are  too  fragmentary  to  be  readily  correlated  across 
the  interval.  No  attempt  has  been  made  to  restore  their  forms  and  com- 
pute their  volumes,  l)ut  it  is  evident  by  inspection  that  they  included  no 
ri^•al  of  the  great  delta  above.  Their  renmants  do  not  exceed  in  total  bulk 
the  mass  the  river  has  dug  from  the  upper  terrace.  They  can  have  no 
value  as  a  basis  for  time  ratios,  because  it  is  impossible  to  tell  how  nnich 
they  owe  to  the  reworking  of  the  material  of  the  higher  delta  and  how 
much  to  the  annual  tribute  of  gravel  brought  by  the  river  from  the  mount- 
ains ;  Init  they  serve  to  show,  first,  that  the  lake  lingered  by  the  way  as  it 
receded  from  the  Provo  shore,  and  second,  that  its  lingerings  were  not  long. 

The  same  lingei'ings  have  left  record  within  the  Provo  delta  in  the 
form  of  stream  terraces,  which  abound  near  the  mouth  of  the  canyon.  Mr. 
Russell  has  recognized  ten  independent  benches  on  the  north  side  of  the 
stream  and  three  on  the  south. 

The  view  in  PI.  XX^^1I  was  sketched  from  the  wall  of  the  Mormon 
temple  standing  on  one  of  the  lower  terraces.  It  exhibits  the  Provo  delta, 
divided  by  the  alluvial  valley  and  overlooked  by  the  Bonneville  shore 
mark,  which  happens  to  Ik;  strengthened  immediately  above  the  delta  by 
an  accumulation  of  shore  drift. 

The  main  delta,  and  probably  all  lielow  it,  rest  upon  a  sloping  floor  of 
lacustrine  sand  and  clay.  The  modern  bed  of  the  river  runs  below  the 
bases  of  the  deltas  and  within  the  zone  of  these  sediments,  Ijut  exposures 
are  rare,  l)y  reason  of  tlie  tendency  of  the  uncemented  delta  gravel  to  slide 
down  and  overplace  it.  The  best  exhibition  at  the  time  of  our  examination 
was  afforded  by  a  fresh  excavation  for  an  irrigation  canal  along  tlie  bluff 
north  of  the  river,  and  was  sketched  by  Mr.  Russell.  The  strata  show 
many  undulations  beneath  the  Provo  delta,  but  are  relatively  smooth  be- 
yond its  margin.  Mr.  Russell  suggests  that  the  disturbance  of  the  strata 
may  have  been  an  incident  of  the  building  of  the  delta.  At  every  stage  of 
the  work  there  was  a  diftei-ence  between  the  weights  borne  1j}'  the  lake 
beds  beneath  the  delta  and  by  those  beyond  it,  and  the  line  of  sej^aratiou 
was  sharply  drawn  at  the  edge  of  the  deposit.     The  conditions  were  there- 

MON  I 11 


](J2  LAKE  BONNEVILLE. 

fore  favorable  for  the  deformation  of  the  freshly  deposited  sediments  by 
differential  jjressnre,  some  of  the  softer  layers  being  made  to  flow  out  from 
beneath  the  gravel.  The  difference  in  weight  between  the  water  on  one 
side  and  the  saturated  gravel  on  the  other  amounted  to  seventy-five  pounds 
to  the  square  inch.  As  the  delta  was  progi-essively  increased  by  additions 
at  the  outer  margin,  the  zone  of  unecjual  pressure;  was  correspomlingly  ad- 
vanced, until  the  whole  substructure  of  the  delta  hail  been  subjected  to  the 
action  and  deformed  as  far  as  its  constitution  permitted. 

fnmo  Vrlta, 


Temple  Delta 

FLond.    PtaOv 


yv  E. 

Fig.  27. — Partial  soctinii  of  Dolta.s  at  Lo^^aii,  Utah,     liy  I.  C.  KuasoU.    Vi-rtical  scalo  greatfr  than  hdrizunlal. 

Wherever  the  body  of  the  Provo  delta  is  freshly  exposed,  it  displays 
an  oblique  lamination  inclining  in  the  direction  of  the  lakeward  margin- 
The  dip  near  the  top  of  the  deposit  is  15  or  20  degrees,  and  diminishes 
downward,  the  layers  being  disposed  in  sweeping,  parallel  curves.  Only 
a  single  locality  exhibited  (1880)  the  nearly  horizontal  beds  which  in  a 
normal  delta  overlie  the  inclined — a  point  half  a  mile  below  the  canyon's 
mouth,  where  the  south  bluff  of  the  river  had  freshly  fallen  down,  exposing 
ninety  feet  at  the  top  of  the  face.     The  series  consists  of: 

r>.  Fine  sand,  5  feet. 

4.  Gravel,  horizontally  laminated,  10  feet. 

3.  Fine  sand,  'i.')  feet.  / 

2.  A  line  of  small  boulders,  unconformable  to  No.  1. 

1.  Gravel,  coarse  and  fine  intermingled;  dipping  15°  toward  the  SW.    Exposed  50  feet. 

Other  Deitas.-Of  tlic  otlicr  sti'eams  of  Cache  Valley,  as  many  as  eight  built 
Provo  deltas,  and  one.  Spring  Creek,  probably  formed  also  a  small  Bonne- 
ville delta.  The  Cub  Creek  and  High  Creek  deltas  are  small,  and  lie  within 
the  flaring  mouths  of  the  canyons.  Smithfield  and  Bell  ville  Creeks  heaped 
their  tribute  just  outside  the  canyons.  Blacksmith  and  Muddy  Forks  de- 
bouched close  together  and  built  a  confluent  delta,  larger  perhaps  than  that 
of  the  Logan,  but  less  symmetric.  The  original  or  ante-Bonneville  canyon 
of  Blacksmith  Fork  was  so  deeply  cut  that  tlie  modem  .stream  lias  not  yet 
removed  all  the  debris  gathered  during  the  lake  period.     The  mass  of  allu- 


L'  S.  0EOL(iGlCAI.  Srn\  KY 


1„\KK  BlIN.VEVlLLK    PI,  XV\  I 


THE  ANCIENT  DELTAS  OF  LOGAN  RH'ER,  AS  SEEN  FROM  THE  TEMPLE. 


INTERNAL  STRUCTURE  OF  LOGAN  DELTAS.        16;3 

viiun  stored  in  it  at  the  Provo  epoch  was  great,  and  contributed  to  the 
t'orniation  at  lower  levels  ot"  a  fine  series  of  deltas,  on  which  stands  the  village 
of  Hyruni.  Spring  Creek  issued  from  a  canyon  which  was  never  cut  down 
to  the  Provo  level,  and  the  apex  of  its  Provo  delta  was  (piite  outside  the  can- 
\(tn.  The  modern  stream  is  a  mere  rivulet  that  one  may  leap  across;  but 
its  delta  liad  a  radius  of  two-thirds  of  a  mile,  "^llie  history  of  the  Bear  River 
deposits  was  not  a\  ell  made  out.  At  the  canyon  mouth  the  river  now  Hows 
at  a  level  a  few  feet  higher  than  before  the  lake  })eriod,  and  tliat  level  is  four 
Imndred  feet  below  the  highest  lake  shore;  but  the  modern  river  outside  the 
canyon  is  walled  in  by  a  great  deposit,  chiefly  of  sand,  through  which  it  has 
opened  a  passage.  There  was  clearly  no  Bonneville  delta  at  this  point. 
The  upper  surface  f)f  the  sand  is  a  sloping  plain,  joining  the  mountain  near 
the  canyon  only  fifty  feet  below  the  Bonneville  shore.  Unfortunately  the 
examination  was  made  while  snow  lay  on  the  ground,  and  the  structure  of 
the  deposit  could  not  be  seen.  If  it  is  a  delta  it  is  probably  of  the  Provo 
date,  and  its  outer  margin  must  be  in  the  vicinity  of  Battle  Creek  Butte,  ten 
miles  away.  Otherwise  it  must  be  regarded  as  a  lake  sediment,  which  owes 
its  exceptionally  great  volume  to  the  proximity  of  a  silt-bearing  river.  In 
either  case  its  source  of  material  is  the  river  drift;  and  in  either  case  its  ac- 
cumulation was  probably  contemporaneous  with  that  of  the  deposits  which 
filled  Gentile  Valley,  a  small  opening  among  the  mountains  at  the  head  of 
the  canyon. 

Outside  of  Cache  Valley  all  the  notable  deltas  except  that  of  the  Sevier 
River  lie  at  the  western  base  of  the  Wasatch  Range.  The  most  northerly 
is  near  Brigham  City,  on  Box  Elder  Creek, ^  a  stream  rising  in  a  small  valley 
just  east  of  the  main  axis  of  the  range,  and  cutting  across  it.  In  the  upper 
valley  there  are  remains  of  a  detrital  filling-,  which  was  probably  coe\al 
with  Lake  Bonneville,  although  not  in  visible  contiimity  with  delta  forma- 
tions. The  canyon  through  the  mountain  has  been  swept  clean  of  debris, 
except  at  the  bottom ;  and  at  its  mouth  there  is  a  small  composite  delta,  of 
which  the  highest  element  has  the  Provo  height. 

The  history  of  Ogden  River  is  nearly  the  same,  but  its  features  are  on 
a  larger  scale.  The  upper  valley  contained  so  large  a  bay  that  a  discernible 
shore-line  was  carved  therein  ;  and  it  is  probable  that  some  of  its  sloping  ter- 

'  Not  to  be  confounded  with  the  Box  Elder  Creek  of  Tooele  Valley,  mentioned  in  connection  with 
the  Grantsville  embankments. 


164  LAKE  BONNEVILLE. 

races  are  remnants  of  Bonneville  deltas.  The  fall  of  the  lake  drained  the 
upper  valley  and  led  to  the  building  of  a  broad  delta  just  outside  the  mouth 
of  the  canyon;  but  this  delta  is  exce})tional  to  the  general  rule  in  that  it  is 
somewhat  below  the  Provo  horizon.  On  the  plain  beyond  it  a  series  of  ter- 
races were  afterwards  formed  similar  to  those  at  Logan.  The  city  of  Ogden 
stands  at  the  end  of  the  series,  and  its  suburbs  encroach  on  some  of  the 
lower  benches. 

Close  to  the  Ogden  deltas  lie  those  of  the  Weber,  less  synunetric  l)ut 
far  more  massive.  They  extend  from  four  to  six  miles  in  nil  diroctions  from 
the  mouth  of  the  canyon.  The  channel  cut  through  them  by  the  modern 
river  is  several  hundred  feet  deep,  and  is  exceptionally  indirect,  curving 
through  the  fourth  part  of  a  circle.  The  broad  flood  plain  within  it  supports 
three  agricultural  hamlets,  and  is  traversed  by  the  Union  Pacific  liaihvay. 
The  westward-bound  passenger  issuing  from  the  rock-bound  defile  of  the 
Wasatch  at  Uinta  Station  finds  himself  enclosed  by  walls  of  delta  sand,  and 
does  not  fully  emerge  from  the  lowest  terraces  until  he  reaches  Ogdt'U  (Sta- 
tion, a  ride  of  eight  miles.  The  greater  portion  of  the  stnicture  lies  on  the 
left  or  south  bank  of  the  river  and  is  locally  known  as  the  Sand  Ridge.  It 
is  the  largest  of  all  the  deltas  of  the  ancient  lake  biiilt  upon  an  open  ])lain, 
but,  owing  to  the  lightness  of  its  material,  the  details  of  its  form  are  imper- 
fectly preserved.  Portions  of  the  interior  of  the  mass  ap])oar  to  be  gravelK', 
but  the  upper  parts  are  chiefly  composed  of  sand,  so  fine  as  to  be  moved 
by  the  wind.  The  ])rincipal  terrace  is  at  the  Provo  level,  and  upon  this 
there  stands  a  liill  more  than  200  feet  high,  which  niav  p(issi])lv  l)e  the 
remnant  of  a  more  ancient  and  more  lofty  delta,  but  is  probably  a  dune 
accumulated  during  the  Provo  epoch.  The  lower  terraces,  marking  the  I'e- 
cession  of  the  water,  were  built  on  the  north  side.  The  south  fai'e  of  tlie 
Provo  delta  has  been  supei-ficially  modified  by  subsequent  wave  action. 

City  Creek,  the  stream  supplying  Salt  Lake  City  with  water,  rises  in 
the  Wasatch  Range  and  flows  through  a  long  canyon  before  emerging  on 
the  plain.  This  canyon  was  capable  of  storing  a  large  amount  *)f  alluvium; 
and  it  is  probably  due  to  this  fact  that  the  Provo  delta  is  smaller  than  tliose 
at  lower  levels.  The  group  of  deltas  constitute  "the  bench"  on  both  sides 
of  the  creek,  and  are  composed  of  coarse,  \\ell  rounded  gravel.     While  they 


OTHER  DELTAS.  165 

were  forming,  a  large  amount  of  sliore  drift  soems  to  liave  readied  tlie  lo- 
cality from  the  southeast,  and  this  modified  the  resulting  topograjihic.  iorms. 
The  configiu'ation  of  the  bench  owes  nearly  as  nuich  to  the  action  of  waves 
as  to  the  depositiini  of  stream  drift. 

The  deltas  formed  by  Little  Cottonwood  and  Big  Cottonwood  Creeks 
coalesced  with  each  other,  and  probably  with  one  from  the  Dry  Cotton- 
wood; but  their  outlines  are  greatly  obscured  by  subsequent  stream  erosion, 
and  they  have  been  further  modified  by  a  system  of  faidts. 

P^ollowing  the  l)ase  of  the  Wasatch  southward,  the  next  delta  i-eached 
is  that  of  American  Fork,  already  described.  Beyond  it,  is  the  delta  of  the 
Provo  River,  a  broad  low  terrace  of  gravel  spreading  fan- wise  from  the 
mouth  of  the  Provo  canyon.  The  radius  of  the  fun  is  about  4^  miles,  and 
the  terrace  has  a  marginal  height  of  70  feet.  It  is  skii'ted  rather  th;ni  di- 
vided by  the  modern  river,  which  turns  abruptly  southward  from  the  mouth 
of  its  canyon.  Lower  deltas  were  only  obscui'ely  differentiated,  but  the 
form  of  the  lake  shore  indicates  that  the  river  is  now  constructing  one. 
The  wagon  road  from  Provo  to  Pleasant  Grove  crosses  the  mniii  delta;  the 
railroads  pass  around  it. 

Near  Provo  City  a  small  stream  named  Rock  Creek  issues  from  a  short, 
steep  canyon  in  tlie  mountain.  It  built  a  small  delta,  during  the  Pxnuieville 
epoch,  and  another  during  the  Provo;  and  these  would  afford  an  instructive 
study  in  chronology  Avere  it  not  for  the  injury  they  have  suffered  from  the 
recent  faulting.  Hobl)le  Creek,  which  irrigates  the  farms  of  Springville, 
built  a,  well-marked  delta  at  the  Provo  level,  and  proliably  a  small  one  at 
the  Bonneville.  The  subaei-ial  alluvium  here  rests  so  high  against  the 
mountain  that  it  constituted  the  coast  at  the  Provo  stage,  and  the  Provo 
delta  rests  against  it.  Five  miles  southward  Spanish  Fork  issues  from  the 
range,  with  a  northwesterly  course.  In  the  Boimeville  lake  it  built  a  delta 
with  a  radius  of  4,000  feet,  and  in  the  Provo  lake  a  larger  delta  coalescing 
with  that  of  Hobble  Creek.  At  Payson  a  small  creek  formed  a  delta  at  the 
Provo  level.  Salt  Creek,  the  next  stream  issuing  from  the  range,  reached 
the  ancient  lake  only  after  flowing  for  some  distance  across  the  j^lain.  Its 
highest  delta  appears  to  be  one  at  the  Provo  horizon,  and  lies  at  the  south 
end  of  Goshen  Valley. 


166  LAKE  BONNEVILLE. 

Apart  from  the  di-ainage  system  of  the  Wasatch,  only  three  deltas  ^A-ere 
observed.  A  small  one  lies  in  an  open  canyon  back  of  the  town  of  Port- 
age, in  Malade  Valley.  A  larger  was  pro])ably  foi-nied  by  Beaver  Creek 
at  the  Provo  level  near  George's  Ranch;  but  it  is  difficult  in  this  case  to 
distinguish  stream  drift  from  shore  drift. 

The  deltas  of  the  Sevier  River  are  more  important.  At  the  Bonneville 
epoch  alluvial  terraces  were  built  where  the  river  enters  Juab  Valle}-,  but 
the  topography  did  not  |)ermit  the  formation  of  a  broad  fan.  At  the  ProA^o 
epoch  a  broad,  low  delta  fan  was  built  by  the  river  on  the  i^lain  between 
Lemington  and  Deseret. 

summary.-The  contributious  made  by  the  phenomena  of  the  deltas  to  the 
history  of  the  oscillations  of  the  lake  may  be  summarized  as  follows: 

First,  the  Bonneville  shore-line  antedates  the  Provo. 

Second,  the  Provo  epoch  was  several  times  longer  than  the  Bonneville. 

Third,  in  falling  from  the  Bonneville  shore  to  the  Provo  the  water  lin- 
gered very  little,  if  at  all. 

Fourth,  in  falling  from  the  Provo  level  to  the  bottom  of  the  basin  the 
water  occasionally  lingered,  but  its  lingerings  were  brief  as  compared  to 
the  halt  at  the  Provo  level. 

Fifth,  the  water  lingered  during  its  advance  antecedent  to  the  Bonne- 
ville epoch,  not  standing  long  at  one  level,  but  oscillating  up  and 
down. 

A  cei'tain  significance  attaches  likewise  to  the  absence  of  deltas  from 
the  greater  portion  of  the  coast  of  the  old  lake.  All  of  the  olil  deltas  are 
associated  with  modern  streams;  and  all  the  modern  streams  of  iiuportance 
built  deltas.  It  would  appear,  then,  that  the  ancient  climate  did  not  create 
important  strc^^ams  in  regions  where  the  outflow  is  now  small.  In  the  west- 
ern portion  of  the  basin,  there  are  catchment  districts  of  considerable  extent 
which  furnish  little  or  no  water  to  the  lowlands  by  reason  of  the  scantiness 
of  rainfall.  If  the  rainfall  in  Bonneville  times  Avas  very  great,  as  compared 
to  the  modern,  these  catchment  districts  should  liavc  furnislicd  tributarv 
streams;  and  such  streams,  flowing  over  tracts  of  alluviuni,  the  accunndation 
of  ages,  should  have  transported  large  quantities  of  it  ti)  the  margin  of  the 
lake  and  constructed  deltas  of  it.     We  seem  thus  to  have  an  intimation  that 


THE  HISTORY  TOLD  BY  DELTAS.  167 

the  climatic  change,  whatever  its  nature,  did  not  affect  the  rainfall  in  a  de- 
firree  commensurate  with  the  difference  in  area  of  lake  surface. 


TUFA. 


Calcai-eous  tufa  was  deposited  by  many  and  perhaps  all  of  the  Pleis- 
tocene lakes.  In  Lake  Lahontan  and  the  other  lakes  of  the  western  portion 
of  the  Great  Basin,  great  masses  were  accumulated,  and  their  study  has 
resulted  in  an  important  contribution  to  the  Pleistocene  history.  In  Lake 
Bonneville  very  little  tufa  was  foiTned,  and  its  bearing  upon  the  history  of 
the  lake  seems  to  be  unimportant.  It  is  associated  exclusively  with  the 
shores;  and  its  amount  upon  individual  shore-lines  is  in  a  general  way  pro- 
portional to  the  magnitude  of  the  other  shore  features.  At  least  this  rule 
applies  to  the  Bonneville,  Intermediate,  and  Provo  shoi'e-lines.  The  Provo 
carries  most  of  all;  the  Bonneville  and  Intermediate  have  an  equable  dis- 
tribution. 

Next  to  tlie  Provo  the  Stansbury  is  most  generously  supjdied;  Init  this 
shore  is  not  characterized  by  endiankments  and  cliffs  of  great  magnitude. 
The  extent  of  the  lake  was  so  greatly  reduced  at  this  stage  that  the  i)ower 
of  the  Avaves  was  materially  lessened;  and  it  is  ])erhaj)s  legitimate  to  infer 
that  the  tufa  records  a  })rotracted  lingering  of  the  falling  water  which  does 
not  find  adequate  expression  in  other  shore  features. 

In  embankments  the  ])osition  oecnpicd  liy  the  tufa  is  on  the  Aveather 
face  a  few  feet  lower  than  the  crest.  It  lies  just  beneath  the  surface,  and 
has  the  function  of  a  cement,  binding  the  gravel  together  into  a  conglomerate. 
Tlie  association  is  far  from  being  invariable;  and  indeed  the  majority  of  the 
emT)ankments  are  uncemented.  In  regions  of  excavation  the  tufa  occurs 
just  outside  the  edge  of  the  cut-terrace,  coating  the  lower  slope  for  a  space 
of  20  or  30  feet.  Its  zone  of  maximum  deposition  was  probably  from  10 
to  20  feet  beneath  the  water  surface. 

Where  the  deposit  is  thin,  it  consists  merely  of  a  uniform  film,  but 
wherever  it  acquires  a  thickness  of  an  inch  or  more,  there  is  manifested  a 
tendency  to  assume  dendroid  forms.  These  are  not  uniform  in  character, 
but  generally  consist  of  branching  stems,  an  eighth  or  a  fourth  of  an  inch 


168 


LAKE  BONNEVILLE. 


in  diameter,  frequently  dividing  and  again  joining,  so  as  to  constitute  a 
reticulated  mass  in  which  the  interspaces  are  not  large. 

The  composition  is  shown  ])y  the  following  analysis,  copied  from  the 
report  of  the  Fortieth  Parallel  Survey,  Vol.  1,  page  502: 

Analysis  of  Tufa\froin  Maiv  Terrace,  liedding  SpriiKj,  'Suit  Jake  Desert,  by  li.  JV.  Wooduard. 

[Specific  gravity,  2.4,  2.3,  2.4.] 


Silicic  acid  (cbiefly  iucluiled  sand) 

Alumina 

Sfsquiosidu  of  iron 

Lime  

Ma<;ne8ia 

Soda 

Potassa 

Litbia    ...    

Phosphoric  acid 

AV  ater 

Carbonic  arid 

Total 


Percentages. 

First, 
sample. 

Second 
sample. 

8.40 

B.22 

1.31 

'.20 

Tr. 

Tr. 

40.38 

i.  50 

3.54 

3.  .52 

0.48 
0.22 

0.54 
0.22 

Tl. 

Tr 

Tr. 

Tr. 

1.71 
38.20 

1.62 
38.33 

100.24 

100. 14 

On  p.iges  495  and  496  of  the  same  volume,  the  microscopic  cliaracters 
of  tlio  tufa  are  described  by  King. 

The  distribution  of  the  tufa  along  each  shore  is  independent  of  the 
nature  of  the  subjacent  terrane.  The  heaviest  observed  deposits  are  upon 
quartzite  and  granite  at  a  considerable  distance  from  calcareous  rocks.  The 
most  conspicuous  accumulations  are  upon  rock  in  place,  but  this  difference 
probably  depends  u])on  the  fact  that  deposits  upon  unconsolidated  material 
are  largely  interstitial.  A  more  important  peculiarity  of  the  distribution  is 
its  relation  to  wave  action.  No  deposit  is  found  in  sheltered  bays;  and  on 
the  open  coast  those  points  least  protected  from  the  fury  of  the  Avaves  seem 
to  have  received  the  most  generous  coating.  These  characters  indicate,  first, 
that  the  material  did  not  have  a  local  origin  at  the  shore  but  was  derived 
from  the  normal  lake-water;  second,  that  the  surf  afforded  a  determining 
condition  of  deposition.     It  will  appear  in  a  later  chajiter  that  calcareous 

'The  analysis  is  headed  "Thiuolite  (pseudo  Gay-Lussite)  " — prohably  thnmjih  inadvertence,  for 
the  reference  to  the  analy.sis  in  the  text  (p.  4%)  iise.s  the  dpsit;nation  tufa  only  ;  and  the  iheory  in  res-ird 
to  the  origin  of  the  Lahontan  tnfa  which  is  cnihodicd  in  llic  term  "psendo  Gay-Lussite,"  appears  from 
the  context  not  to  have  been  applied  to  the  Bonneville  basin. 


TUFA.  169 

matter  constitutes  an  important  part  of  the  fine  sediment  of  the  hike  bottom, 
and  that  this  was  chiefly  or  wholly  precipitated  from  solution.  It  is  not 
easy  to  see  why  this  deposition  should  consist  of  discrete  particles  in  the 
open  lake  and  be  welded  into  a  continuous  mass  upon  the  shore;  but  a  par- 
tial explanation  a})pears  to  be  afforded  by  the  hypothesis  that  the  separation 
was  promoted  by  the  aeration  of  the  water.  All  precipitation  being  initiated 
at  the  surface  during  storms,  coalescence  at  the  shore  niay  ha\'e  resulted 
from  contact  at  the  instant  of  separation.  The  suggestion  finds  a  certain 
amount  of  support  in  the  part  played  by  nuclei  as  determinants  of  precipi- 
tation. 

The  thickest  deposit  anywhere  observed  is  on  the  outer  verge  of  the 
Provo  terrace  at  the  north  end  of  Reservoir  Butte,  where  there  is  a,  maxi- 
mum of  four  feet.  The  tufa,  there  coats  a  knob  of  solid  quartzite  so  situated 
that  while  it  was  fully  exposed  to  the  surf,  whatever  the  direction  of  the 
wind,  it  was  exempt  from  attack  by  shore  drift.  The  locality  is  exceptional; 
in  most  places  where  the  tufa  is  so  abundant  as  readily  to  attract  attention, 
its  depth  is  measured  by  inches. 

An  allied  deposit  may  be  mentioned  in  this  connection,  namely,  oolitic 
sand.  This  was  fiist  observed  on  the  Bonneville  shores  by  Miss  Susan 
Coolidge,  of  Grantsville,  Utah,  and  was  afterward  found  by  Messrs.  W.  J. 
McGee  and  George  M.  Wright  on  several  shore  terraces  at  the  north  end  of 
the  Oquirrh  Range.  It  is  now  forming  in  Great  Salt  Lake  along  the  coast 
between  the  delta  of  the  Jordan  and  Black  Rock,  where  it  constitutes  the 
material  of  a  beach,  and  is  drifted  shorcAvard  in  dunes.  Like  the  tufa,  it  is 
exclusively  a  shore  formation,  but  the  circumstances  connected  with  its 
occurrence  on  the  modern  shores  of  Gi'eat  Salt  Lake  and  Pyramid  Lake 
warrant  the  suspicif)n  that  it  is  not  e(iually  independent  of  local  sources  of 
supply.  The  locality  mentioned  on  the  shore  of  Great  Salt  Lake  is  near 
the  mouth  of  a  stream  whose  annual  tribute  of  carbonate  of  lime  can  not 
be  small,  and  the  only  known  locality  on  Pyramid  Lake  is  associated  with 
hot  calcareous  springs. 

RE8UMfi. 

The  highest  of  the  shore-lines  jireserved  on  the  slopes  of  the  basin, 
namely,  the  Bonneville  shore-line,  has  an  altitude  of  1,000  feet  above  Great 


170  LAKE  BONNEVILLE. 

Salt  Lake.  By  reason  of  its  position  at  the  top  of  the  series,  it  is  the  most 
conspicuous  of  all;  but  the  one  most  deeply  carved  is  the  Provo,  375  feet 
lower.  Between  the  Bonneville  and  Provo  are  the  Intermediate  shore- 
lines, characterized  by  embankments  of  great  size,  but  without" correspoiid- 
ingly  great  sea-clifFs  and  terraces.  Below  the  Provo  tlie  .slopes  exliiljjt  lake 
sediments,  with  occasional  shore-lines  superposed.  Of  these  latter  the  Staus- 
bury  is  the  most  prominent. 

The  area  of  the  lake  at  the  Bonneville  stage  was  19,750  square  miles; 
at  the  Provo  stage,  about  13,000  square  miles;  at  the  Stansbury  stage,  about 
7,000  square  miles. 

The  order  of  sequence  of  the  shores  to  which  names  have  been  given 
is:  first.  Intermediate;  second,  Bonneville;  third,  Provo;  fourth,  Stansbury. 
During  the  period  of  the  formation  of  the  Intennediate  embankments,  tliere 
were  no  persistent  water  stages;  but  the  water  surface  oscillated  uj)  and 
down.  The  last  additions  to  the  embankments  were  made  during  a  gen- 
eral advance  of  the  water.  The  oscillation  of  the  water  surface  continued 
through  the  Bonneville  epoch,  the  Bonneville  shore  representing  the  cnm- 
bined  results  of  wave  action  at  a  series  of  water  levels  having  a  vertical 
range  of  20  feet.  The  last  stage  of  this  series  was  the  liigliest,  and  imme- 
diately afterward  the  surface  fell  ra})i(lly  to  the  Provo  horizon,  where  it 
remained  a  long  time.  The  water  margin  afterward  receded  from  the 
Provo  shore  to  its  present  position,  halting  occasionally  by  the  way,  and 
longest  at  the  Stansbury  sliore. 


CHAPTER    IV. 

THE  OUTLET. 

Tliirteen  years  ago  I  had  the  temerity  to  predict,^  first,  that  the  position 
of  the  Bonneville  shore-line  would  eventually  be  shown  to  have  been  deter- 
mined by  an  overflow  of  the  lake,  and  second,  that  the  Provo  shore-line 
would  be  found  to  have  been  similarly  determined.  The  first  of  these  pre- 
dictions has  been  verified  in  its  letter,  but  not  in  its  spirit;  the  second  has 
proved  to  have  full  warrant.  My  anticipation  was  based  on  the  following 
consideration:  A  lake  without  overflow  has  its  extent  determined  by  the 
ratio  of  precipitation  to  evaporation  within  its  basin;  and  since  this  ratio  is 
inconstant,  fluctuating  from  year  to  year  and  from  decade  to  decade,  it  is 
highly  improbable  that  the  water  level  will  remain  constant  long  enough  to 
permit  its  waves  to  carve  a  deep  record.  I  failed  to  take  account  of  the 
fact  that  the  highest  shore-mark  of  the  series  is  conspicuous  by  reason  of 
the  contrast  there  exhibited  between  land  sculptni-e  and  littoral  sculpture. 
We  now  know  that  the  height  of  the  Bonneville  shore-line  was  determined 
in  a  certain  sense  by  overflow,  since  a  discharge  limited  the  rise  of  the 
water;  but  the  carving  of  the  shore  was  essentially  completed  before  the 
discharge;  and  as  soon  as  that  began,  the  water  level  fell.  At  the  Provo 
horizon,  on  the  contrary,  a  constant  or  nearly  constant  water-level  was 
maintained  by  discharge  for  a  very  long  time. 

The  outlet  of  a  lake  is  necessarily  across  the  lowest  point  of  the  rim  of 
its  basin;  and  it  is  essential  that  this  point  be  somewhat  lower  than  the 
water  level  of  the  lake.  The  search  for  an  outlet  to  Lake  Bonneville  was 
therefore  a  search  for  a  pass  in  the  rim  of  the  basin  lower  than  the  neigh- 

'  Expl.  West  of  the  100th  Mer.,  vol.  3,  pp.  90,  91. 

171 


172  LAKE  BONNEVILLE. 

boring  shore-lines.  It  is  e(|ually  necessary  tluit  tli(!  liasin  on  the  opposite 
side  of  tlie  ])ass  he  connj)etent  to  receive  the  discharged  water.  It  nnist 
either  drain  to  tlic  ocean  or  else  be  snfficiently  large  and  suflicicntl\'  arid  to 
dispose  of  tlie  afflncnt  water  ])y  evaporation.  TIh^  conditions  of  outlet 
having  been  satisticd,  and  a  discharge  having  been  produced,  it  is  ('(|ual]y 
evident  that  the  process  of  that  discharge  would  modify  the  topographv  in 
a  peculiar  manner.  A  channel  would  be  produced  at  the  pass,  and  this 
would  descend  in  one  direction  only,  its  sides  and  bottom  merging  at  the 
pass  into  other  topographic  features.  The  site  of  the  ancient  outlet  of  Lake 
Bonneville  should  therefore  exhibit  a  channel,  the  bed  f)f  which  is  lower 
than  the  contiguous  shore-line,  and  the  de.scent  of  which  is  toward  some 
basin  competent  to  receive  and  dispose  of  the  water. 

It  is  quite  C(mceivable  that  a  basin  like  tlie  l)onneville,  known  to  ])e 
subject  to  deformation  through  hypogene  agencies,  should  discharge  its 
surplus  water  at  one  time  over  one  pass  and  afterward  over  another;  and 
this  possibility  was  one  of  the  considerations  leading  to  an  examination  i>f 
its  entire  coast  line.  By  that  examination  it  was  ascertained  that  all  the 
lower  passes  of  tlie  basin's  rim  are  at  the  north,  se})arating  the  basin  from  the 
drainage  system  of  the  Columbia  River.  These  passes  were  systematically 
visited  by  competent  observers;  and  it  was  ascertained  that  the  Bonneville 
waters  discharged  at  one  point  only. 

The  trend  of  the  mountain  ranges  in  that  region  is  generally  north  and 
south  and  the  passes  are  siinjdy  culminating  points  in  the  intervening  valleys. 
As  a  rule  they  are  not  rocky,  but  con.sist  of  alluvium,  the  profiles  of  which 
rise  gently  toward  the  mountains  on  either  side.  South  of  each  sm/h  pass 
the  minor  drainage  lines  from  each  mountain  unite  and  produce  a  main 
drainafje  channel  descendino:  toward  the  basin  of  Great  Salt  Lake.  At  tlie 
north  a  similar  confluence  produces  a  drainage  channel  descending  toward 
the  tributaries  of  the  Columbia.  On  the  pass  the  alluvial  profiles  from  the 
mountains  unite  with  gentle  curvature;  and  there  is  no  channel  of  drainage. 

It  is  a  curious  fact  that  in  a  region  characterized  by  great  reliefs  of  sui-- 
face,  a  munber  of  passes  were  so  nearlv  at  the  same  level  that  a  difierence 
of  only  a  few  feet  determined  the  actual  point  of  discharge.  The  water  of 
the  lake  rose  within  75  feet  of  the  pass  north  of  Kelton,  where  the  Boisd 


SEARCH  FOR  THE  OUTLET.  173 

stage-road  crosses  from  the  Salt  Lake  basin  to  the  head-waters  of  Raft  River; 
and  it  rose  Avitliin  100  feet  and  200  feet,  respectively,  of  the  passes  north  of 
Snowsville  and  Curlew. 

Red  Rock  pass.-Tlie  actual  point  of  discharge  was  at  the  north  end  of  Cache 
Valley,  at  a  point  known  as  Red  Rock  Pass;  the  outflowing  river  entered 
Marsh  Creek  valley,  and  being  there  joined  by  the  Portneuf,  flowed  through 
Portneuf  Pass  to  the  valley  of  the  Snake  River.  The  first  suggestion  of 
its  position  was  by  Bradle}',  who  crossed  the  old  channel  some  miles  l)elow 
the  ])ass  in  1872;  and  it  was  independently  demonstrated  l)y  Mr.  Gilbert 
Thompson  and  by  the  writer,  wlio  separately  visited  the  localit-s^  some  years 
later.^ 

The  ascent  to  Red  Rock  l*ass  from  Cache  Valley  is  so  gentle  as  to  be 
scarcely  noticeable,  and  the  descent  on  the  opposite  side,  while  ]ijerceptible 
to  the  eye,  affords  an  easy  grade  to  the  Utah  and  Northern  Railroad.  A 
few  miles  west  of  the  pass,  there  rises  a  lofty  mountain  ridge  separating 
Cache  Valley  and  Marsh  Valley  from  Malade  Valley.  On  the  east  are 
lower  mountains,  separating  Cache  Valley  and  Marsh  Valley  from  Gentile 
Valley  and  Basalt  Valley.  From  the  base  of  the  range  on  either  side,  an 
alluvial  slope  descends  to  the  pass,  but  this  is  not  continuous.  Knobs  of 
indurated  rock,  similar  to  those  constituting  the  mountain,  project  through 
it,  testif}'ing  to  the  existence  a  short  distance  beneath  the  alluvium  of  a  rocky 
sj)ur  comiecting  the  two  ranges.  At  a  few  points  there  are  exposui-es  of 
less  indurated  rocks,  supposed  to  be  of  Tertiary  age,  but  these  form  no  hills 
by  themselves,  being  buried  under  the  alluvium  except  where  laid  bare  by 
recent  erosion.  The  alluvium  is  further  interrupted  by  the  clianncl  of  the 
ancient  outlet,  which  is  one  of  the  most  notable  features  of  the  landscape. 
It  has  been  excavated  to  a  depth  of  several  hundred  feet,  and  has  a  general 

I  It  was  iiiiiintained  by  I'eale  tliat  tlie  orii;inal  point  of  discharge  was  at  Portneuf  Pass  instead  of 
Red  Rock  Pass;  and  the  discussion  of  tliis  view  gave  to  the  subject  of  the  onth-t  and  its  discovery  a, 
more  voluniiuous  literature  than  perhaps  it  deserved.  The  writer's  diss  nt  from  Pcale's  determination 
has  already  been  recorded  in  discussing  the  supremacy  of  the  Bonneville  shoreline  (p.  94).  Readers 
who  care  to  pursue  the  subject  further  will  fiud  the  following  references  useful :— G.  K.  Gilber*,  in  Sur- 
veys Wist  of  the  100th  Meridian,  vol.  3,  Geology,  p.  91 :  E.  E.  Howell,  idem,  p.  'Jr.l  ;  F.  H.  Bradley, 
Oeol.  Survey  of  Terr.,  Ann  Rept.  for  1872,  pp.  'JO'^,  20:i ;  Gilbert,  Bull.  Phil.  Soc,  Washington,  vol.  2, 
p.  103:  A.  C.  Peale,  Geol.  Survey  of  Terrs.,  Ann.  Rept.  for  1^~7,  pp.  565,  642;  Am.  Jour.  Sci.,  3d  series, 
vol.  15,  1H7H,  p.  C5;  Gilbert,  idem,  M  Series,  vol.  15,  1878,  p.  256;  Peale,  idem,  vol.  15,  1878,  p.  439; 
Gilliert,  idem,  vol.  19,  1880,  p.  342;  Lieut.  Willard  Young,  Surveys  West  100th  Meridian,  Ann.  Rept. 
for  1878,  n.  121. 


174  LAKE  BONNEVILLE. 

width  of  about  one-third  of  a  mile.  Five  small  streams  flow  from  the 
mountains  to  the  ancient  channel,  and  each  of  these  has  carved  a  deep 
trench  in  the  alluvium,  casting  the  eroded  mateinal  into  the  channel.  The 
gi-eatest  of  the  streams  is  Marsh  Creek,  debouching  at  Hunt's  Ranch;  and  its 
freshly  formed  deposit  occupies  the  old  channel  for  a  distance  of  nearly  three 
miles.  Three  or  four  miles  farther  south  Five  Acre  Creek  makes  a  similar 
tribute,  filling  the  old  channel  with  alluvium  for  the  space  of  a  mile;  and 
the  same  thing  is  repeated  on  a  smaller  scale  by  Stockton  Creek,  two  miles 
farther  south.  The  alluvial  fan  built  by  Marsh  Creek  is  a  few  feet  higher 
than  the  others,  so  that  the  actiial  water  parting  is  at  Hunt's  Ranch. 

Between  the  Marsh  Creek  and  Five-Acre  Creek  alluvia,  the  old  chan- 
nel is  occupied  by  a  marsh  three  miles  in  length  with  an  average  width  of 
twelve  hundred  feet;  and  Avithin  this  there  is  a  small  pond.  Between  the 
alluvia  of  Five-Acre  Creek  and  Stockton  Creek  there  is  a  larger  pond,  known 
as  Swan  Lake.  These  marshes  and  ponds,  whenever  they  accumulate  \\ater 
enough  to  overflow,  drain  sovithward  to  Cache  Valley;  and  all  the  streams 
of  the  pass  except  Marsh  Creek  are  tributary  to  them.  ]\Iarsh  Creek  turns 
abruptly  north  on  entering  the  channel  and  flows  toward  Marsh  Valley.  Its 
volume  is  so  small  that  during  the  dry  season  it  does  not  maintain  a  super- 
ficial flow  through  the  valley,  but  repeatedly  sinks  beneath  the  smface  and 
reappears  below  in  springs. 

The  knobs  of  indurated  rock,  which  in  the  immediate  vicinit}'  of  the 
pass  consist  of  arenaceous  limestone,  both  adjoin  and  interrupt  the  chan- 
nel. Near  Hunt's  Ranch  there  are  two  buttes,  each  several  hundi-ed  feet  in 
height,  overlooking  the  channel  from  opposite  sides,  and  between  them  are 
a  nmnber  of  low  reefs  projecting  throvigh  the  flood-])lain  of  ]\Iarsli  Creek 
Constricted  by  these  reefs,  the  channel  has  a  mininnnn  superficial  widtli  of 
only  GOO  feet. 

The  relations  of  these  various  features  will  be  better  imderstood  by 
reference  to  the  map  in  PI.  XXVKI. 

The  Bonneville  shore-line  is  traceable  continuously  about  Cache  Valley 
to  the  vicinity  of  the  pass.  On  the  east  side  its  most  noi'therly  vestige  is 
upon  a  butte  a  mile  south  of  Hunt's  Ranch.  On  the  west  side  it  is  lost  on 
the  alluvial  slope  two  miles  from  Hunt's  Ranch.     Its  height  above  the  marsh 


U  S. GEOLOGICAL   SURVEY 


liAKE   BOMNE'/ILLZ,    PL  Xr^lir 


MAP  OF  THE 


OUTLET  OF  l^VIvE  BONNEVILLE 


R  E  D  R  0  C  Iv   P  ASS. 


Oneida  Co  Idalio 


Toj)Oqraph\    hv   h^  J) . John  son  . 
Ofoloqy    b\  GK  Gilberi 


Soiitieiille    .S'htwehne 


o  Vi  1 


SCALE      I  I =4   WILE 

3.^'0  iet't    (hntoars 


ji^^'-       ^Oiierrt  ^lltwuil     Deposits  . 


.luHus  Iticn  A  t'o.lilli 


Di  ovm  In-  G  TliompM 


RED  ItOCK  PASS.  175 

betAveen  Marsh  and  Five-Acre  creeks  is  340  feet.  The  nearest,  point  at 
which  the  Provo  shore-line  was  observed  is  about  eight  niih's  farther  south, 
in  the  vicinity  of  the  town  of  Oxfoi'd. 

Marsh  Creek  issues  from  its  canyon  in  the  mountains  aljout  two  and 
one-half  miles  east  of  the  old  channel.  The  intervening'  sjjfice  is  occupied 
by  a  sloping  alluvial  plain  terminating  in  a  bluff.  It  is  evident  that  this  is 
an  alluvial  fan  or  alluvial  cone  constructed  by  the  creek  before  the  exca- 
vation of  the  Bonneville  outlet.  It  was  afterward  partially  eroded  by  the 
outflowing  river,  and  also  by  Marsh  Creek,  which  has  excavated  a  passage 
several  hundred  feet  in  depth. 

Where  this  old  alluvial  plain  approaches  nearest  to  the  Bonneville 
channel,  its  edge  is  fifty  feet  higher  than  the  nearest  terrace  of  the  Bonne- 
ville shore,  and  a  restoration  of  its  profile  indicates  that  it  coalesced  with 
slopes  from  the  opposite  mountain  range  at  about  the  level  of  the  Bonne- 
ville shore.  A  careful  study  of  the  ground  has  satisfied  the  writer  that  the 
base  or  outer  margin  of  the  alluvial  cone  was  part  of  the  ancient  water- 
parting,  and  was  the  point  at  which  the  outflow  was  initiated. 

The  fact  that  the  Bonneville  water  discharged  at  first  over  a  barrier  of 
alluvium  instead  of  solid  rock  had  much  to  do  with  the  subsequent  history 
of  the  lake.  Uncemented  alluvium  is  easily  and  rapidly  torn  up  and  re- 
moved, and  as  soon  as  a  current  began  to  flow  across  the  divide,  it  must 
have  commenced  the  excavation  of  a  channel.  As  the  channel  increased, 
the  vokime  of  the  escaping  water  became  greater,  and  this  increase  of  vol- 
ume reacted  on  the  power  of  erosion.  In  a  short  time  a  mighty  river  was 
formed,  and  the  lowering  of  the  lake  surface  resulted.  For  a  time  the  out- 
pouring was  a  veritable  debacle,  and  it  could  not  have  assumed  the  phase 
of  an  ordinary  river  commensurate  with  the  inflow  of  the  lake  until  the  allu- 
vial barrier  was  completely  demolished  and  the  resistance  of  the  limestone 
reef  was  called  into  play.  When  the  corrasion  of  the  channel  had  proceeded 
so  far  as  to  give  the  river  a  bed  of  limestone,  the  process  of  excavation  was 
changed  from  the  mere  transportation  of  loose  detritus  to  the  corrasion  of 
solid  rock,  and  the  rate  of  excavation  was  greatly  diminished.  We  have 
here  the  ex2)lanation  of  the  rajiidity  of  the  final  recession  of  the  lake  from 
the  Bonneville  level  to  the  Provo. 


176  LAKE  r.ONNEVlLLE. 

Marsh  Valley—Marsh  Vulk'}',  like  Cache  Valle}',  is  ench).sed  Ijetween  mount- 
ain ranges,  and  has  a  north  and  south  trend.  Its  length  is  aljout  thirty-five 
miles,  and  its  greatest  width  is  eight  or  ten  miles.  Twenty  miles  from  Red 
Rock  Pass,  the  Portneuf  River  breaks  through  the  eastern  mountain  chain 
and  enters  the  valley,  turning  northward  and  running  parallel  ^\itli  Mai-sh 
Creek  to  the  end  of  the  valley.  There  it  receives  the  creek  and  then  tiii-ns 
abruptly  westward  and  escapes  from  the  valley  through  a  deep  liut  ojx-n 
canyon.  The  upper  canyon  of  the  Portneuf  has  at  some  time  admitted  hna 
as  Avell  as  water.  A  succession  of  basaltic  coulees  have  poured  thi-ough  it 
into  Marsh  Valley  and  have  followed  the  slope  of  the  valley  to  the  lower 
canyon.  The  Portneuf  River  follows  the  western  mai-gin  of  the  lava  beds, 
and  i\Iarsh  Creek  the  eastern,  each  occu])ying  a  narrow  valley  sunk  from  'M) 
to  100  feet  below  the  level  of  the  lava  table.  A  comparison  of  these  val- 
leys illustrates  the  disparity  between  Marsh  Creek  and  its  channel.  I'urt- 
neuf  River  is  several  times  larger  than  Marsh  Creek;  l)ut  the  inuncdiatc 
valley  liy  which  it  is  contained  is  smaller.  Indeed,  there  is  every  evidence 
that  the  valley  of  Marsh  Creek,  having  been  formed  by  the  ancient  Bonne- 
ville river,  is  now  in  process  of  filling.  It  abounds  in  meadows  and  marshes, 
and  at  one  point  contains  a  lakelet. 

The  River.-It  a})pears,  however,  that  the  Bonneville  river  was  nut  citn- 
tained  during  its  entire  existence  in  the  channel  now  ((ccuj)ied  by  Mar.-li 
Creek.  The  whole  upper  surface  of  the  lava  tongue,  where  it  has  a  width 
of  more  than  a  mile,  is  fluted  and  polished,  and  pitted  with  pdt-holes  after 
the  manner  nf  a  river  bed;  and  there  seems  no  escape  from  the  condusidn 
that  it  was  swept  l)y  a  broad  and  rapid  current.  The  trenches  at  the  side 
of  the  lava  may  or  may  not  then  have  existed;  l)ut  even  if  they  did  not, 
we  have  to  contemplate,  as  the  agent  of  corrasion,  a  river  comparable  with 
Niagara.  Indeed  it  is  even  possibles  that  Niagara  might  suifer  by  com- 
parison. 

Let  us  assume  that  at  the  time  the  Bonneville  river  travtu'sed  the  la\a- 
bed  the  lower  channel  at  the  side  had  not  been  eroded;  and  let  us  furtlu-r 
assume  that  its  width  was  somewhat  less  than  that  of  thi'  lava, — sa\'  one 
mile.  When  the  river  came  into  being,  the  total  descent  of  its  bed,  from 
one  end  of  Marsh  Valley  to  the  other,  was  at  the  rate  of  13  feet  to  the  mile. 


THE  DEBACLE.  177 

In  the  last  stages  of  its  existence  its  average  grade  in  the  same  space  was  7 
feet  to  the  mile.  At  all  stages  the  declivity  was  greater  near  the  pass  than 
in  the  lower  end  of  Marsh  Valley.  Let  us  assume  that  the  slope  of  the 
water  surface  in  flowing  over  the  lava  was  2^  feet  to  tlie  mile,  or  one  foot 
in  2,000.  If  now  we  assume  in  addition  that  the  discharge  equaled  that  of 
the  Niagara  Rivei',  we  have  all  the  data  necessary  for  computing  the  mean 
depth;  and  A\e  obtain  ftir  that  depth  9  feet.  To  one  who  stands  upon  the 
lava  bed  and  notes  the  scale  of  the  carvings  which  ornament  its  surface, 
this  determination  appears  for  too  small.  Twenty  feet  would  better  accord 
whh  the  phenomena,  and  twenty  feet  woidd  discharge  the  flood  volume  of 
the  Missouri. 

Another  evidence  of  the  magnitude  of  the  outflow  is  found  at  the  pass. 
West  of  the  swamp  there  is  an  irregular  terrace,  extending  from  Swan  Lake 
to  Red  Rock,  the  upper  surface  of  which  is  corrugated  with  parallel  furrows 
and  I'idges  trending  in  the  general  direction  of  the  current.  These  consist 
partly  of  limestone  crags  and  partly  of  alluvium.  Comparing  them  with 
similar  flutings  in  other  stream  beds,  they  ap^iear  to  be  explicable  only  as 
details  of  channel-bottom  wrought  by  a  torrent  of  great  volume. 

How  long  the  discharging  river  maintained  its  colossal  dimensions  can 
not  be  learned,  but  the  period  certainly  w^as  not  great.  The  entire  prism  of 
water  between  tlie  Bonneville  and  Provo  planes  would  be  discharged  by 
the  Niagara  channel  in  less  than  25  years;  and  if  the  Bonneville  river 
reached  a  greater  size,  it  could  liave  maintained  it  only  for  a  shorter  time. 

It  is  evident  that  the  channel  at  the  pass  has  been  partly  filled  since 
the  desiccation  of  its  river;  but  the  precise  amount  of  filling  is  not  so  evi- 
dent. A  crude  estimate  was  based  U2)on  the  configuration  of  certain  small 
drainage  lines  tributary  to  it.  Before  the  filling  began,  these  drainage  lines 
(as,  for  example,  that  of  Gooseberry  Creek;  see  PI.  XXVIII)  found  their 
base  of  erosion  in  the  main  channel,  and  adjusted  their  profiles  thereto. 
As  the  filling  of  the  channel  progressed  they  were  likewise  partially  filled 
near  their  mouths;  and  a  study  of  their  configuration  yields  a  crude  esti- 
mate of  the  amomit  of  deposition.  It  is  judged  to  be  about  thirty  feet; 
and  if  this  estimate  is  con-ect,  the  bottom  of  the  channel  is  370  feet  lower 
than  the  Bonneville  shore.  This  is  approximately  equal  to  the  difference  in 
MON  I 12 


178  LAKE  BONNEVILLE. 

level  of  the  Bonneville  and  Provo  sliores  and  it  serves  to  connect  the  testi- 
mony of  the  outlet  with  that  of  the  shore-lines. 

It  is  not  easy  to  estimate  the  cross  section  of  tlic  channel  of  outflow  at 
any  stage  of  its  existence.  Undouhtedly  it  was  broader  and  deeper  while 
its  walls  and  bed  consisted  of  alluvium  than  afterward  when  solid  rock  was 
reached.  The  trough  now  occupied  by  the  marshes  and  Swan  Lake  i)roba- 
bly  represents  its  width  after  rapid  corrasion  had  ceased  ;nid  before  tJH^  tiiial 
desiccation  of  tlic  lake  was  begun;  but  this  is  a  mere  surmise.  We  ncc<l  not 
doubt  that  it  had  a  greater  width  at  an  earlier  stage  and  a  less  width  at  a 
later. 

As  the  degradation  of  tiie  channel  proceeded,  the  position  of  its  iiead 
was  continually  transferred  southward.  The  discharge  was  initiated  on  tlie 
Marsh  Creek  alluvial  fan  two  miles  north  of  Hunt's  lianch;  but  during  its 
final  stages  the  oiitflowing  river  headed  seven  miles  farther  south,  between 
Swan  Lake  ami  the  Round  Valley  marsh.  When  the  outflow  ceased,  the 
water  parting  between  the  Bonneville  and  Snake  River  })asins  was  r.t  tliis 
latter  })oint,  Gooseberry  and  Five  Acre  creeks  being  tributary  to  the  Snake 
River.  Li  the  course  of  time,  however,  the  alluvium  de])osited  by  Marsh 
Creek  effectually  dammed  their  channel  and  tui-ned  their  di'ainage  south- 
ward. Mar.sh  Creek  itself  must  normally  alternate  in  its  affiliation.  As  its 
alluvial  fan  has  gradually  increased,  its  debouchure  must  have  been  shifted 
from  Marsh  Valley  to  Cache  Valley  and  vice  versa  many  times.  Even  now, 
in  the  irrigati(Mi  of  farming  land  at  Hunt's  Ranch,  a  j)ortion  of  its  water  is 
sometimes  artificially  turned  toward  the  Great  Basin. 

The  Gate  of  Bear  River. -Cache  Vallcy  is  Separated  from  the  open  l»asin  of 
Great  Salt  Lake  by  a  mountain  range  wliicli  at  one  place  is  low.  Tlirougli 
this  the  Bear  River  escai)es  from  the  valley  by  a  narrow  passage  between 
precipitous  walls  of  Ihnestone.  During  the  Boimeville  epocli  the  dividing 
ridge  was  submerged  at  several  places,  so  that  the  waters  of  tiie  Cache 
Valley  bay  conmuxnicated  freely  with  those  of  the  open  lake.  During  the 
Provo  epoch  the  connection  was  restricted  to  the  ^jassage  now  occu])ied  by 
the  river,  a  strait  only  a  f(!W  hundred  feet  broad  and  a  mile  and  a  lialf  in 
length.  One-half  of  the  present  water  suppl\-  of  (ireat  Salt  Lake  is  derived 
from  Bear  River,  and  tliat  river  during  the  Provo  epoch  was  a  tribut^iry  of 


liii    ft 


CACHE  VALLEY  A  DISTRIBUTING  EESEKVOIK.  179 

Cache  Bay.  Cache  Bay  therefore  presumably  received  half  of  the  inflow  of 
tlic  Provo  lake;  aiul  it  is  from  Cache  Bay  that  the  outflow  discharged.  If 
tlic  \()luiue  of  outflow  was  greater  than  the  tribute  brought  by  Bear  River, 
I  he  difference  was  supplied  by  a  current  from  the  main  lake  through  the 
narrow  strait  into  Cache  Bay.  If  the  volume  of  Bear  River  was  greater  than 
the  outflow,  then  the  excess  was  discharged  througli  the  strait  into  the  lake. 
Doubtless  in  either  case  the;  flow  through  the  strait  was  regularly  reversed 
by  reason  of  the  annual  inequnlity  of  the  Bear  River  tribute,  and  still  more 
frequently  by  the  eff"ect  of  storm  winds,  but  if  the  volume  of  Bear  River 
greatly  exceeded  that  of  the  outflow,  it  is  conceivalile  that  the  fact  of  out- 
fio.v  did  not  imply  the  perfect  freshness  of  the  lake. 

This  speculation  was  suggested  by  a  curious  piece  of  negative  evidence. 
The  calcareous  tufa  which  abounds  upon  the  Provo  shore  has  not  been  found 
associated  with  it  in  Cache  Valley.  If  it  be  really  absent,  and  not  merely 
undetected,  its  distribution  would  seem  to  indicate  that,  during  at  least  a 
large  portion  of  the  Provo  epoch,  the  outflow  was  less  than,  or  did  not 
greatly  exceed,  the  Bear  River  inflow.  Under  such  circumstances  the  main 
body  may  have  accumulated  carbonate  of  lime  to  the  point  of  saturation, 
while  Cache  Bay  did  not. 

The  lowering  of  the  lake  level  by  the  wear  of  the  outlet  diminished  the 
area  of  the  lake  surface  about  one-third,  and  it  must  have  diminished  the 
annual  evaporation  from  the  lake  surface  by  about  the  same  amount.  Up 
to  the  moment  of  outflow  the  entire  tribute  of  the  lake  was  disposed  of  by 
evaporation ;  and  if  the  change  of  climate  which  brought  about  the  outflow 
went  no  farther,  the  amount  of  the  discharge  during  the  Provo  e})och  should 
have  been  one-third  of  the  inflow.  It  is  thus  seen  to  be  quite  within  the  range 
of  possibility  that  Cache  Bay,  receiving  one-half  the  total  inflow,  was  a 
fresher  body  of  water  than  the  main  lake  through  the  entire  Provo  epoch. 
It  is  certainly  most  ren:iarkable  that  a  concurrence  of  geographic  and  climatic 
conditions  should  enable  a  lake  to  maintain  a  higher  degree  of  salinity  than 
the  water  of  the  outlet  limiting  its  size. 

On  the  other  hand,  it  is  not  supposable  that  the  main  body  of  Lake 
Bonneville  was  saline,  or  even  brackish,  as  those  terms  are  ordinarily  used, 
during  the  maintenance  of  the  Provo  level  by  outflow.     The  strait  at  the 


180  LAKE  BONNEVILLE. 

entrance  of  Cache  Bay  was  several  hundred  feet  deep,  and  any  sensible 
difference  in  density  between  the  bay  and  the  open  lake  would  luive  pro- 
duced an  interchange  of  gi-avity  currents,  the  light  water  flowing  from  the 
bay  at  the  surface,  and  the  dense  water  entering  beneath.  Adding  to  this 
regulative  action  tlie  interchange  of  currents  to  and  fro  during  storms  and 
(luring  floods,  it  is  evident  that  only  a  small  difference  in  the  average  (con- 
stitution of  the  bay  water  and  the  lake  water  could  be  maintained.  The 
very  minute  difference  competent  to  produce  the  preci])itation  of  carbonate 
of  lime  in  the  open  lake  would  not  affect  the  practical  freshness  of  the  water. 
It  may  be  remarked  in  passing  that  the  deposition  of  tufa  during  the 
Frovo  epoch  is  not  inconsistent  with  a  contemporaneous  discharge  by  the  lake, 
even  though  Cache  Valley  did  not  operate  as  a  distributing  reservoir  for  the 
Avater  of  Bear  River.  In  a  broad  way,  it  is  true  that  salt  lakes  have  no  dis- 
charge, Avhile  fresh  lakes  have,  and  that  lakes  are  freshened  by  discharge; 
but  so  long  as  the  volume  of  outflow  is  less  than  the  inflow,  the  freshening 
is  a  matter  of  degree.  The  inflowing  streams  bring  a  certain  amount  of 
mineral  matter;  the  outlet  carries  away  a  certain  amount;  and  as  soon  as 
equilibrium  of  action  is  established,  these  two  quantities  are  equal.  If  the 
volume  of  the  outflow  is  only  a  small  fraction  of  the  inflow,  its  salinity  must 
be  greater  in  inverse  ratio:  and,  since  the  salinity  of  the  discharge  is  nor- 
mally identical  with  that  of  the  lake,  the  latter  can  not  be  so  pm-e  as  its 
affluents.  Carbonate  of  lime  is  peculiarly  sensitive  to  the  effect  of  such 
conditions.  On  the  one  hand,  it  is  dissolved  from  the  rocks  by  rain  and 
stream  in  greater  quantity  than  most  other  minerals,  and  on  tlie  other,  its 
point  of  saturation  is  quickly  reached.  It  might  be  precipitated  in  a  lake 
even  while  there  was  free  discharge  of  a  third  part  of  the  inflowing  water. 

The  Question  of  an  Earlier  Discharge.-It  liaS  beCll  SUggCStcd  by  Davls^  that  aUtCrior 

to  the  Bonneville  epoch,  the  altitude  of  the  rim  of  the  basin  may  have  been 
such  that  its  drainage  was  discharged  to  the  ocean  without  the  formation  of 
a  lake,  or  at  least  without  the  formation  of  a  large  lake.  The  more  general 
problem  on  which  his  suggestion  bears  will  be  deferred  to  another  chapter; 
but  it  is  proper  to  inquire  here  whether  there  is  any  indication  in  the  rim  of  the 
basin  of  a  pre-Bonneville  outflow.     The  possibility  of  such  an  outflow  was 

_  '  Lake  Bonneville  [a  review],  by  W.  M.  Davis:  Science,  vol.  1,  1883,  p.  570. 


WAS  THERE  AN  EARLIER  OUTLET?  181 

fully  recognized  by  the  writer  during  his  investigations  in  the  field;  and 
several  of  the  lower  passes  were  visited  with  special  reference  to  this  ques- 
tion. It  was  not  considered  important  to  examine  the  higher  passes,  because 
displacement  of  the  earth's  crust,  while  paroxysmal  in  detail,  appears  in  a 
broad  way  to  be  slowly  progressive,  so  that  the  time  presumably  necessary 
for  lifting  a  barrier  to  a  considerable  height — say  one  thousand  feet — would 
suffice  for  the  obliteration  by  the  processes  of  land  sculpture  of  all  traces  of 
a  preexistent  channel.  The  results  of  the  search  were  purely  negative,  no 
evidence  of  a  pre-Bonneville  channel  being  found.  The  only  poiut  where 
the  indication  is  not  so  clear  as  could  be  desired  is  Red  Rock  Pass.  A  pre- 
Bonneville  outlet,  occupying"  the  same  position  as  the  Bonneville  outlet, 
would  be  very  difficult  to  discover,  especially  if  the  intervening  period  were 
sufficient  for  the  accumulation  of  large  bodies  of  alluvium.  Suppose,  for 
illustration,  that  Red  Rock  Pass  were  to  remain  subject  to  the  existing  con- 
ditions until  Marsh  Creek  was  enabled  to  restore  the  original  contours  of  its 
alluvial  cone.  While  the  Bonneville  channel  would  be  locally  filled  and 
concealed,  other  portions  of  it  would  be  likely  to  remain  visilile ;  and  its 
presence  would  be  betrayed  by  some  such  phenomenon  as  Swan  Lake. 
But  if  the  valley  were  reflooded  and  another  river  traversed  the  pass,  the 
washing  out  of  the  alluvium  would  leave  a  channel  practically  identical 
with  the  present,  and  the  earlier  history  would  he  masked. 

If,  however,  the  interval  between  two  discharges  sufficed  only  for  the 
partial  restoration  of  the  alluvial  contours,  the  duplication  of  the  history  of 
outfiow  would  be  recorded  by  terraces,  and  its  decipherment  would  not  be 
hopeless.^    No  such  terraces  were  observed  at  Red  Rock  Pass. 

These  observations  manifestly  do  not  warrant  the  conclusion  that  tlie 
Bonneville  basin  never  had  free  drainage.  They  indicate  merely  that  the 
last  epoch  of  outflow  antecedent  to  the  Bonneville  was  separated  from  tlie 
latter  by  so  long  an  interval  that  the  channel  of  discharge  can  not  now  be 
discovered. 

THE  OLD  RIVER  BED. 

The  overland  stage  road  which,  before  the  day  of  Pacific  railroads, 
carried  the  mail  across  the  Great  Basin,  skirted  the  southern  margin  of  the 
Great  Salt  Lake  Desert.     From  Salt  Lake  City  to  Canyon  Station,  at  the 


182  LAKE  BONNEVILLE. 

eastern  base  of  the  Deep  Creek  Mountains,  its  route  lay  almost  entirely 
upon  the  bed  of  Lake  Bonneville.  Midway  it  crossed  a  broad  channel, 
which  every  one  recognized  as  an  ancient  river  bed.  Here  a  stage  station 
was  established  and  a  change  of  horses  was  kept.  The  horses  were  not 
watered  l)y  the  river,  nor  even  l)y  a  diminutive  modern  representative  of  it, 
but  by  means  of  a  well  sunk  to  a  depth  of  100  feet.  Now  that  the  road 
has  fallen  into  disuse  and  earth  has  clogged  tlie  neglected  well,  the  chance 
traveller  finds  nothing  to  quench  his  thirst  from  Simpson  spring  to  Fish 
Spring,  a  distance  of  40  miles.  One  wlio  stands  here  in  the  midst  of  a 
desert,  where  the  oidy  vegetation  is  a^.scattenng  gi-owth  of  low  bushes,  and 
looks  on  an  ancient  river  course  2,000  feet  broad  and  more  than  100  feet 
deep,  can  not  fail  to  be  deeply  impressed. 

Naturally  this  old  water  trace  was  associated  in  the  minds  of  observers 
with  the  shore  traces  on  the  flanks  of  the  mountains;  and  it  is  not  surpris- 
ing that  popular  theory  located  here  the  outlet  of  the  lake.^  Nevertheless, 
the  Bonneville  shore-line,  which  is  visible  upon  the  adjacent  mountains  and 
buttes,  is  700  feet  higher  than  the  highest  part  of  the  old  channel;  and  our 
exploration  demonstrated  that  the  entire  site  of  the  channel  was  submerged 
during  both  Bonneville  and  Provo  epochs. 

Neither  end  of  the  channel  is  visible  from  the  crossing  of  the  stage 
road,  but  both  are  commanded  by  neighboring  peaks.  It  is  about  45  miles 
in  length,  and  holds  a  direct  course  from  the  heart  of  the  Sevier  Desert  to 
the  edge  of  the  Great  Salt  Lake  Desert,  passing  between  the  McDowell  and 
Sunpson  Ranges.  Throughout  its  extent  it  is  cut  from  tlie  clays  deposited 
by  the  ancient  lake.  Near  the  extremities  these  only  are  exliibited  in  its 
banks ;  but  in  the  middle  course,  where  it  follows  the  base  of  the  McDowell 
Mountains  and  associated  buttes,  it  lays  bare  the  older  rocks  at  several 
points.  Its  general  width  is  about  half  a  mile,  lint  it  expands  in  places  to 
nearly  a  mile,  and  is  elsewhere  constricted  to  about  1,000  feet.  At  the 
south  its  depth  is  small,  and  its  southern  end  is  ill  defined,  the  cliannel 
features  gradually  losing  themselves  in  the  jdain  of  tlie  Sevier  Desert. 
Its  northern  end  is  more  definite,  being  bordered  by  low  bluffs;  and  thence 

'Seo  A.  S.  Packard  in  Bull.  U.  S.  Geol.  Suiv.  Trrr.,  2iul  8«ri.w,  vol,  1,  p.  413  (No.  .''>);  an.l  G.  K. 
Gilbert,  Amer.  Jour.  Sci.,  3(1  nor.,  vol.  10,  187C,  p.  228. 


'J  S. GEOLOGICAL    SUP,VEY 


LAKE  BOMKE^TLLE.    PL.XXXI 


Juliua  BirnAOu.UUi 


DroHTi  bv  (•  Thompsoi 


THE  OLD  RIVER  BED.  183 

to  the  River  Bed  Station  its  depth  increases  to  130  feet.  In  the  pass  be- 
tween the  mountains  its  Ijanks  coalesce  with  the  steep  faces  of  huttes;  and 
its  general  depth  may  he  several  hundred  feet. 

This  description  applies  merely  to  its  present  condition.  There  is  good 
reason  to  holieve  that,  at  the  time  of  its  desiccation,  it  was  deeper,  especially 
in  the  southern  part.  Everywhere  it  is  margined  by  easily  eroded  lake 
sediments;  and  near  the  mountains  the  surfoce  of  these  lies  at  such  an  angle 
that  every  rain  washes  down  an  abundance  of  mud  into  th(^  old  channel. 
On  the  Salt  Lake  Desert  the  ])lain  is  so  nearly  level  that  superficial  waters 
have  little  power  of  erosion,  and  the  silting  of  the  channel  has  been  less. 
In  the  vicinity  of  the  pass  the  recent  deposit  lias  a  probable  depth  of  100 
to  200  feet. 

The  general  descent  of  the  channel  is  from  south  to  north,  but  this 
is  interrupted  at  one  point  in  the  pass  by  an  alluvial  dam,  over  which  the 
water  seems  to  find  its  way  rarely.  The  direction  of  the  original  descent,  or 
the  direction  of  drainage  through  the  channel,  is  not  demonstrated  by  the 
existing  levels;  but  fortunately  there  is  other  evidence  in  the  shape  of  a 
terrace,  marking  a  flood-plain  of  the  ancient  stream  when  its  channel  was 
half  excavated.  This  appears  on  the  banks  of  the  channel  north  of  the 
River  Bed  Station,  and  is  capped  by  a  deposit  of  fine  gravel,  the  pebbles  of 
which  are  evidently  derived  from  the  McDowell  and  Simpson  Mountains. 

From  the  head  of  the  chamiel  the  plain  of  the  Sevier  Desert  descends 
southward  for  many  miles;  and  it  is  evident  that,  when  the  channel  was 
occupied  by  a  river,  the  desert  was  covered  by  a  lake.  In  a  word,  the 
channel  was  opened  at  a  time,  during  the  final  desiccation  of  the  lake, 
when  the  level  of  tlie  water  in  the  main  body  fell  below  the  l)ottom  of  the 
strait.  The  inflow  of  the  Sevier  body  was  for  a  time  greater  than  its  re- 
stricted lake  surface  could  discharge  by  evaporation,  and  the  surplus  flowed 
over  the  pass  to  the  main  body,  opening  a  channel  as  it  flowed.  The  upper 
lake  thus  preserved  on  the  Sevier  Desert  Avas  both  small  and  shallow,  and 
its  shore  marks  have  not  been  identified.  The  lower  lake  was  large,  and 
may  have  left  a  well  marked  shore  record;  but  this  has  not  been  discrimi- 
nated from  others  on  the  margin  of  the  desert.  A  rough  estimate,  based  on 
a  general  knowledge  of  the  contours  of  the  country,  indicates  that  the  up- 


184  LAKE  BONNEVILLE. 

per  lake  had  one-eleventli  the  area  of  the  lower.  The  lake  system  had  also 
another  member,  for  the  Bonneville  shore  had  then  receded  from  Utah  Val- 
ley, and  the  outlet  of  Utah  Lake  was,  as  now,  an  affluent  of  the  Great  Salt 
Lake  basin.  The  continuance  of  the  climatic  decadence  finally  lowered 
SeAaer  Lake  below  the  level  of  outflow  and  dried  tlie  liver  bed. 

It  has  already  been  remarked  that  even  in  the  i)ass  between  the  mount- 
ains the  river  bed  was  carved  from  the  lacustrine  strata  deposited  by  Lake 
Bonneville.  The  Bonneville  strata  there  rest  against  steep  faces  of  the 
rocky  buttes;  and  the  relation  of  these  faces  to  each  other,  and  to  the  gen- 
eral course  of  the  channel,  indicates  that  they  are  the  walls  of  an  older 
channel  whose  course  the  post-Bonneville  river  followed.  The  history  of 
this  older  channel  is  unknown ;  and  its  discovery  only  tells  us  that,  at  some 
unknoAvn  period  before  the  lake,  there  was  free  da-ainage  from  one  desert  to 
the  other.  Tliere  seems  no  waj^  to  determine  in  which  direction  this  drain- 
age led,  nor  whether  either  plain  was  covered  by  a  lake. 

OTHER   ANCIENT   RIVERS.  ' 

• 

Three  other  long  abandoned  stream  courses  have  been  observed  within 
the  basin.  One  of  these  has  already  been  mentioned.  The  pass  between 
Rush  and  Tooele  valleys  is  now  dammed  across  by  a  great  system  of  wave- 
built  bars,  which  prevent  the  drainage  of  Rush  Valley  from  passing  through 
Tooele  Valley  to  Great  Salt  Lake.  Against  this  dam  the  water  of  Rush 
Valley  sometimes  accumulates  in  a  lakelet  known  as  Rush  Lake,  and  tliis 
lakelet  occupies  a  portion  of  the  ancient  drainage  channel.  It  has  a  width 
of  1,000  feet,  and  is  shallow.  Doubtless  the  depth  of  the  channel  has  been 
considerably  diminished  by  recent  deposits;  and  if  these  were  cleared  aAvay 
the  width  of  its  bed  would  be  found  smaller  than  the  indication  given  by 
the  lake. 

This  channel  is  interpreted  as  showing,  not  that  there  was  anciently  in 
Rush  Valley  a  water  supply  com])etent  to  override  and  remove  such  a  liar- 
rier  as  noAV  restrains  it,  but  merely  that,  before  the  creation  of  the  Bonne- 
ville lake,  the  valley  had  free  drninage  northward. 

A  larger  channel,  whose  habit  indicates  a  stream  comparable  with  the 
smaller  rivers  of  the  basin,  enters  Snake  Valley  from  the  south  at  a  point 


OTHER  OLD  RIVERS.  185 

just  east  of  Wlieeler  Peak  known  as  the  Snake  Valley  Settlement.  The 
channel  ends  at  the  margin  of  the  old  lake,  and  appears  to  have  contained 
a  stream  triljutary  to  the  lake,  which  disappeared  at  the  same  time.  It  is 
now  occupied  near  the  settlement  by  a  streamlet  from  the  adjacent  mount- 
ain known  as  Lake  Creek,  but  this  enters  the  channel  at  its  side,  and  played 
no  important  jiart  in  its  formation.  Above  its  confluence  the  channel  has 
essentially  the  same  dimensions,  and  these  continue  as  far  as  it  was  traced, 
about  twenty  miles  from  its  mouth.  Circumstances  did  not  permit  its  far- 
ther exploration. 

Near  its  mouth  the  ancient  stream  cut  across  the  base  of  an  immense 
alluvial  fan,  poured  out  from  Wheeler  Peak,  opening  a  channel  1,000  feet 
broad,  which  retains  a  depth  of  50  feet.  A  secondary  alluvial  fan,  formed 
by  the  same  mountain  stream,  and  from  the  material  amassed  in  the  first, 
was  afterwards  thrown  across  the  channel,  damming  it  and  causing  a  small 
lake.  Still  more  recently  this  dam  was  broken  through  and  a  smaller  chan- 
nel Avas  opened,  whereby  the  lake  was  nearly  drained,  and  Lake  Creek 
escaped  to  Snake  Valley.  The  closing  chapter  of  the  history  has  been  con- 
tributed by  man.  The  denizens  of  the  little  hamlet  have  built  another  dam 
within  the  small  channel  (a  puny  and  insignificant  affair  compared  with 
those  of  Nature's  construction),  whereby  they  have  created  a  pond  for  the 
storage  of  water  for  iri'igation. 

A  third  stream  course  of  some  magnitude  enters  the  basin  in  Idaho  at 
the  north  end  of  Snowsville  Valley,  dc'bouching,  fi'om  a  mountain  at  the  west, 
almost  precisely  at  the  divide  between  the  drainage  of  the  Basin  and  that 
of  the  Snake  River.  It  was  not  traced  toward  its  source,  l)ut  the  grade  of 
its  bed  indicates  that  it  drains  a  valley  of  some  size  within  the  mountains. 
Its  flood-plain  has  a  breadth,  just  before  it  reaches  the  Bonneville  horizon, 
of  2,000  feet,  and  below  that  liorizon  is  covered  by  the  lake  sediments. 
Within  the  lake  area  it  can  be  traced  for  several  miles,  although  lined 
throughout  by  the  lacustrine  deposits.  Through  this  channel  water  rarely 
finds  its  way  at  the  present  time.  The  flood-plain  is  covered  by  soil  and 
vegetation,  which  give  no  evidence  of  recent  disturbance  except  along  a 
narrow  meandering-  trench  that  one  may  leap  across.  There  is  here  no 
delta  associated  with  the  Bonneville  shore,  and  the  implication  seems  to  be 


186  LAKE  BONNEVILLE. 

that  the  locality  was  characterized  at  tsome  very  ancient  date  by  a  climate 
more  liumid  than  either  the  lionneville  or  the  present. 

With  tliese  exceptions  the  water  courses  of  the  drier  coasts  are  not 
known  to  give  evidence  of  modification.  All  of  them  are  larger  than  the 
ordinary  streams  within  them  require;  but  the  extraordinary  requirements 
in  an  arid  region  are  so  great  that  the  channels  do  not  seem  abiKjnnal. 

OUTLETS  AND  SHORE-LINES. 

The  harmony  between  the  conclusions  based  on  the  phenomena  of  the 
shore-lines  and  those  derived  from  the  features  associated  with  tlie  outlet 
lias  a  double  bearing.  On  the  one  hand,  it  serves  to  establish  the  elements 
of  the  lake's  history  thus  far  set  forth;  and  on  the  other  it  defines  tlu^  in- 
fluence of  outflow  on  shore  topogra2)hy.  Without  outflow  the  level  of  a 
lake  is  inconstant  and  oscillatory,  and  unless  the  water  stands  long  at  the 
same  level  the  waves  will  not  excavate  cliffs  and  ten-aces  comparable  in 
magnitude  with  the  embankments  constructed. 

It  follows  that  the  Stansbury  shore,  which  gives  e\'idence  t)f  a  perma- 
nent water  stage,  not  merely  by  its  cliffs  and  terraces  but  by  its  accumula- 
tion of  tufa,  was  determined  by  an  outflow  or  its  equivalent.  At  one  time 
I  supposed  that  the  problem  f»f  its  existence  would  be  solved  by  the  Old 
River  Bed — that  its  level  would  be  found  to  have  been  determined  by  a 
discharge  from  the  main  Ijody  to  the  Sevier  body;  but  this  hypothesis  was 
was  overthrown  by  the  study  of  the  river  bed,  which  showed  the  discharge 
to  have  been  northward  instead  of  southward.  The  precise  relation  of  the 
Stansbury  shore  to  the  river  bed  has  not  been  ascertained,  for  the  shon^  has 
not  been  recognized  in  that  -sdcinity,  but  they  do  not  differ  greatly  in  alti- 
tude. It  is  probable  that  during  the  Stansbury  epoch  the  main  lake  did 
not  extend  to  the  Sevier  Desert.  There  is  one  other  valley  Avhich  might 
have  served  as  a  reservoir  for  surplus  water  at  the  Stansbury  stag(>,  Init  tlie 
connecting  strait  has  not  been  critically  examined.  White  Valley  contained 
a  large  bay  during  both  the  Bonneville  and  Provo  epochs,  and  was  deej) 
enough  to  have  received  a  considerable  discharge  at  the  Stansl>ury  stage,  if 
the  strait  was  adjusted  to  its  delivery.  Its  area  is  indeed  small  as  compared 
to  the  main  lake  at  that  level,  but  it  might  none  the  less  have  served  as  a 


THE  STANSBUKY  PROBLEM.  187 

regulator,  causing  the  oscillating  lake  to  linger  at  a  particular  level  each 
time  it  rose. 

The  nature  of  the  problem  embodied  in  the  Stansbury  shore  was  not 
realized  until  the  field  examinations  were  so  nearly  complete  that  the  op- 
portunity had  passed  for  visiting  the  localities  important  for  its  discussion. 
It  therefore  remains  as  one  of  the  unanswered  questions  developed  by  the 
investigation. 


CHAPTER   V. 
THE  BONNEVILLE  BEDS. 

A  certain  series  of  lacustrine  strata  have  been  designated  tlie  Bonne- 
ville beds.  Tlieir  relation  to  the  old  shore-lines  was  first  pointed  out  by 
Hayden/  and  afterward  by  the  geologists  of  the  Fortieth  Parallel  Siu'vey 
and  the  Wheeler  Survey.  The  grounds  for  the  correlation  have  not  been 
distinctly  enunciated,  probably  because  they  are  so  patent  to  each  obsers^er 
that  their  statement  seems  surperfluous.  In  the  present  work,  however,  it 
is  proposed  to  combine  the  history  derived  from  the  sediments  with  the 
history  derived  from  the  shore  record;  and  there  is  a  logical  necessity  for 
establishing  the  general  synchronism  of  the  two. 

A  brief  account  has  already  been  given  of  the  Tertiary  lacustrine  strata 
observed  in  the  Bonneville  basin.  While  these  exhibit  considerable  variety 
in  texture,  they  are  in  general  so  distinct  lithologically  from  the  Bonne^■ille 
beds  that  their  discrimination  has  been  easy  and  uuemban-assed  by  doubt. 
The  Bonneville  lieds  occupy  the  lowlands,  constituting  nearly  the  entire 
surface,  and  retain  the  attitude  of  deposition,  Ijnng  flat  on  the  open  plain  or 
gently  inclining  at  the  bases  of  the  mountains.  Wherever  the  outcrops  of 
the  Tertiaiy  beds  are  associated  with  these,  they  exhiliit  dips  referable  to 
displacement,  and  they  are  overlain  tuiconformably  by  the  Bonneville.  Tlie 
Bonneville  beds  are  thus  seen  to  be  the  latest  lacustrine  deposit  of  the  basin, 
and  this  fact  indicates  tlieir  synchronism  with  the  latest  littoral  evidence  of 
a  lacustrine  condition. 

Again,  the  distribution  of  the  Bonneville  beds  is  strictly  limited  l)y  the 
Bonneville  shore-line;  and  none  of  the  other  groups  are  so  limited.  The 
latter  are  thus  shown  to  be  older  than  the  shore-lines.     The  Bonne%nlle 

'  Snn-pictures  of  Rocky  Mountain  Scenery,  by  F.  V.  Haydeu,  New  York,  1B70,  p.  1S2;  Auu. 

Kept.  Geol.  Survey  Terr,  for  1870,  p.  170. 
188 


COEEELATION  OP  SEDIMENTS  AND  SUOKE-LINES.  189 

beds  are  not  traceable  outward  from  the  center  of  the  basin  to  all  parts  of 
the  Bonneville  shore-lines,  or  at  least  they  do  not  to  that  limit  hold  their 
familiar  characters;  but  they  bear  to  the  shore-line  certain  definite  relations, 
\\liich  may  be  stated.  Where  the  margin  of  the  basin  is  steep  and  the 
shore-line  is  high,  the  lake  beds  reach  to  the  foot  of  the  slope;  where  the 
basin  margin  is  gently  inclined,  as  in  the  shallow  bays,  they  extend  nearly 
to  the  outer  limit  of  wave  work. 

Finally,  as  has  been  fully  set  forth  by  King,'  the  Bonneville  beds  are 
in  places  interstratified  with  alluvial  deposits;  they  rest  upon  the  principal 
mass  of  alluvium  from  the  mountains  and  support  alluvium  of  recent  trans- 
portation. Tins  relation  is  strictly  paralleled  by  the  shore-lines,  which  rest 
upon  the  alluvial  cones  of  the  mountain  bases  and  are  themselves  overplaced 
by  recent  alluvium. 

Adding  to  these  facts  the  a  priori  consideration  that  the  deltas  contain 
only  the  coarser  material  brought  by  streams,  the  finer  having  been  car- 
ried in  suspension  to  the  lake,  and  that  the  shore  embankments  represent 
only  the  coarser  part  of  the  product  of  littoral  erosion,  the  finer  having  been 
carried  lakeward  by  the  undertow,  so  that  there  must  have  been  fine  lake 
sediments  contemporaneous  with  the  deltas  and  embankments  of  the  shore, 
the  general  correspondence  of  the  Bonneville  beds  with  the  Bonneville 
shore-lines  is  clearly  established. 

It  is  only  in  regard  to  details  that  the  correlation  is  less  clear  than 
could  be  desired.  One  result  of  the  deposition  of  the  sediments  was  the 
raising  of  the  base  level  of  ex'osion  of  all  streams  tributary  to  the  basin,  so 
as  to  make  them  agents  of  deposition  along  their  lower  courses  in  post- 
Bonneville  time.  The  localities  are  therefore  exceedingly  rare  where  even 
partial  sections  of  the  Bonneville  beds  can  be  observed;  and  it  is  only  at 
their  extreme  outer  limits,  where  they  rise  toward  the  shore,  that  their  base 
is  ever  seen. 

LOWER  RIVER  BED  SECTION. 

The  deepest  section  of  the  lake  beds,  or  more  strictly  the  section  repre- 
senting the  largest  fraction  of  the  Bonneville  Period,  is  exposed  in  the  walls 
of  the  Old  River  Bed  near  the  point  where  it  is  crossed  by  the  Overland 

'  Geol.  40th  Par.,  vol.  1,  p.  493. 


190  LAKE  BJNNEVILLE. 

Stafi;'e-r()ad.     It  lias  some  title  to  be  reg'arded  as  the  typical  section,  and 
exhibits  tlio  following'  iriendjers: 

1.  (At  base.)  The  Yellow  Clay,  a  fine  argillaceous  deposit,  laminated 
throughout,  olive  gray  on  its  fresh  exposure,  but  weathering  to  a  pale  yellow. 
In  this  are  occasional  passages  of  sand,  but  these  are  local  and  discontin- 
uous. Nodules  of  selenite,  consisting  of  grouped  arrow-head  crystals,  are 
abundant;  and  jointage  cracks  sometimes  contain  rosettes  of  recrystallized 
gypsum.  Bivalve  shells  of  several  species  are  included.  The  base  is  not 
seen;  a  thickness  of  90  feet  is  exposed. 

2.  The  White  Marl,  a  fine  calcareous  clay  or  argillaceous  marl,  light 
gray  or  cream-colored  on  fresh  exposure,  nearly  white  on  weathered  sur- 
face. Contains  some  gypsum,  but  less  than  No.  1.  Overlies  No.  1  with 
unconformity  by  erosion,  and  is  at  its- base  crowded  with  shells  represent- 
ing nearly  the  same  fauna.     Thickness,  10  feet. 

3.  The  marl  passes  upward  into  a  fine  sand,  the  transition  being  grad- 
ual and  the  continuity  perfect.  The  sand  contains  also  the  same  species  of 
shells.  Thickness,  about  10  feet,  the  upper  limit  being  obsciu'ed  by  a  recent 
eolian  deposit  of  similar  texture. 

The  distribution  of  the  Yellow  Clay  and  White  Marl  is  universal  through- 
out the  lower  parts  of  the  basin,  and  they  ascend  in  the  shallower  bays 
toward  the  upper  shore-lines.  At  low  levels  their  physical  charactcu-s  undergo 
little  change,  and  they  are  readily  discriminated  by  their  diff"erence  in  color. 
At  very  low  levels  a  yellow  clay  appears  over  the  White  Marl,  blending 
with  it  as  though  continuously  deposited.  This  may  be  the  equivalent  of 
the  sandy  member  in  the  typi(;al  section,  which  is  not  everywhere  foinid. 
The  unconformity  between  the  Clay  and  the  Marl  does  not  include  any 
observed  diff"erence  in  inclination,  and  is  not  always  detectable,  but  it  was 
observed  at  localities  so  widely  distrilmted  as  to  indicate  that  it  is  not  a 
mere  local  phenomenon.  Against  the  steeper  coasts  the  beds  appear  to 
terminate  somewhat  abruptly  at  low  levels;  but  on  gentle  slojies  they  con- 
tinue with  a  change  of  character,  acquiring  sand  both  by  admixture  and  by 
intercalation.  By  these  changes  their  distinctive  chai-acters  are  lost,  and  at 
high  levels  their  separation  is  for  the  most  part  impossible. 


THE  TYPE  SECTION.  191 

The  exposures  of  the  Yellow  Clay  are  so  rare  and  so  small  that  its 
special  mutations  can  not  be  characterized,  but  abundant  opportiniity  is 
atlbrded  for  observation  of  the  White  Marl.  As  the  shore  is  approached,  the 
arenaceous  capping  increases  in  relative  thickness,  encroaching  on  the  marl 
below.  The  base  is  the  last  to  change,  holding  its  white  color  on  many 
l)arts  of  the  coast  to  levels  above  the  Provo  shore. 

At  numerous  points  between  the  Bomieville  and  Provo  liorizons,  sedi- 
mentary deposits  are  seen  to  alternate  with  littoral,  the  former  consisting  of 
marls,  clays,  and  sands,  and  the  latter  of  shore  drift  in  the  form  of  spits  and 
bars.  We  have  not  succeeded  in  correlating  these  sublittoral  deposits  either 
with  each  other  or  with  the  lacustrine  sediments  of  the  center  of  the  basin; 
and  the  phenomena,  although  numerous,  are  so  fragmentary  that  there  seems 
no  advantage  in  placing  their  details  on  record.  Their  only  contribution  to 
the  deduced  history  of  the  lake  is  the  confirmation  they  afford  of  the  con- 
clusion indepeiidently  reached  that  the  surface  of  the  lake,  when  not  limited 
by  outflow,  was  subject  to  many  minor  oscillations. 

At  a  few  localities  there  was  observed  an  abnormal  development  of  the 
lacustrine  section,  a  result  of  what  may  be  called  redeposition.  A  single 
illustration  will  suffice.  Snowsville  Valley  contained  at  the  Bonneville  stage 
a  bay  eight  miles  broad  and  rumiing  twenty  miles  inland.  At  the  Provo 
stage  its  linear  dimensions  were  reduced  one-half,  and  it  became  shallow. 
At  a  later  and  lower  stage,  possibly  the  Stansbury,  the  water  barely  reached 
to  the  entrance  of  the  bay;  and  at  this  time  the  freshly  deposited  muds  of 
the  bay  appear  to  have  been  washed  lakeward  in  great  volume,  accumulat- 
ing at  the  mouth  of  the  bay  in  a  series  of  sheets  inclined  at  an  angle  of  3  or 
4  degrees  toward  the  lake.  This  may  perhaps  be  called  a  delta  deposit,  but 
it  differs  from  typical  deltas  in  the  fineness  of  its  material  and  the  conse- 
quent low  angle  of  crosS  lamination.  The  last  addition  to  the  deposit  con- 
stitutes the  face  of  a  percejjtible  terrace,  ascended  by  the  road  from  Curlew 
to  Snowsville.  Through  this  terrace  Deep  Creek  or  Deseret  Creek,  the  drain 
of  the  valley,  has  excavated  a  channel  from  twenty  to  thirty  feet  in  depth, 
exposing  the  structure  of  the  mass.  The  deposit  has  a  general  resemblance 
to  the  normal  lake  beds,  but  exhibits  four  or  five  alternations  of  the  typical 
yellow  and  white  colors. 


192 


LAKE  130NNEV1LLE. 


LEMINGTON   SECTION. 

The  uiicniif'orinity  of  tlio  White  Marl  upon  the  Yellow  Clay  iiidieates 
(liscoutiimity  of  lacustrine  eouditious;  and  at  two  localities  this  evidence  is 
supplemented  by  the  occurrence  of  subaifrial  d(;posits  at  the  horizon  of  un- 
conformity. ( )ue  of  these  hjcalities  is  at  Lemin«.^-ton,  where  the  .Sevier  River, 
issuing  from  its  narrow  valley  iu  the  Canyon  Range,  enters  the  Sevier 
Desert.  During  the  highest  water  stages,  no  delta  was  foi-med  at  this 
point,  because  the  land-locked  bay  on  the  east  side  of  th(^  range  received 
and  i-etained  all  the  coarser  alluvium;  but  a  great  amount  of  tine  matter  was 
washed  into  the  lake,  and  this  was  deposited  with  exceptional  rapidity  ;d)(Kit 
the  mouth  of  the  estuary.  The  total  local  deposit  must  have  amounted  to 
several  hundred  feet,  and  recent  erosion  by  the  river  has  exposed  150  feet 
of  this  to  view.  The  point  of  sj^ecial  interest  is  just  outside  the  canyon 
mouth,  where  the  lacustrine  strata  are  seen  to  abut  against  the  steep  face  of 


Fig.  2h, — Section  .showing;  snccessiou  nf  Lacnstriiit*  iind  Alluvial  Ut-posits  at  Leniini:t«ii.  Ut'li. 

1.  Piilt'ozoic  sandstoiKV  2.  Tlit!  Yellow  ('lay  (Lower  Homieville).  'i.  \VtHlj;e  of  alluvial  ;irav«l. 
4.  The  White  Marl  (Upper  IJuuneville).  5.  Keceut  alluvial  j;tavel.  G.  liuiiiieville  shore  uutcli,  with 
recent  talus.  , 

quartzite  constituting  the  mountain  front.  The  material  of  the  lake  beds  is 
here  coarser  than  in  the  typical  section,  and  the  contrast  in  color  between 
the  upper  and  lower  series  is  barely  discernible.  The  Yellow  Clay  incdudes 
through  nearly  its  whole  depth  a  considerable  percentage  of  fine  sand,  and 
the  White  Marl  has  a  fine  texture  only  at  its  base,  consisting  above  of  coarse 
and  fine  sands. 


SECTION  ON  THE  SEVIER  RIVER.  193 

Associated  with  the  lake  beds  are  two  wedges  of  alluvium,  the  tliicker 
ends  of  which  abut  ag,ainst  the  quartzite  of  the  mountain.  The  upper  of 
these  is  a  modern  deposit,  receiving-  additions  at  every  storm;  the  loAver, 
which  otherwise  is  similar  in  all  its  characters,  is  inserted  between  the  White 
Marl  and  the  Yellow  Clay. 

The  Marl  and  its  associated  sand  have  here  a  joint  thickness  of  50  feet, 
and  the  Yellow  Clay  a  visible  thickness  of  100  feet,  the  base  being  con- 
cealed. Tlie  Bonneville  shore-line,  here  taking  tlie  form  of  a  terrace  and 
clitf,  runs  50  feet  above  the  upper  limit  of  the  White  Marl  and  120  feet 
above  the  upper  limit  of  the  Yellow  Clay. 

The  series  of  events  by  which  these  relations  were  produced  can  not  be 
mistaken.  While  the  lake  stood  at  a  liigli  level  the  Yellow  Clay  was  de- 
posited against  the  base  of  the  mountain;  and  as  the  de])osit  extends  to 
within  120  feet  of  the  Bonneville  .shore,  the  lake  level  must  have  a])proaclied 
this  maxiiuimi  very  nearly.  Then  the  water  receded  so  for  as  to  l)ring  sub- 
aerial  agencies  locally  into  jjlay.  The  waste  from  the  mountain  face  was 
washed  by  the  rain  into  the  margin  of  the  lacustrine  deposit,  and  accumu- 
lated there  in  a  talus  or  alluvial  slope  of  low  inclination.  Afterward  the 
water  returned,  and  remained  at  a  high  level  during  the  deposition  of  the 
White  Marl;  and  at  the  sanae  time  the  Bonneville  shore  terrace  was  cut  by 
the  waves. 

The  locality  was  carefully  studied  for  the  purpose  of  discovering  other 
intercalary  alluvial  wedges,  but  none  were  found;  and  the  exposures  were 
sufficiently  complete  to  warrant  the  confident  assertion  that  none  exist 
within  the  range  of  the  section.  Their  a])sence  indicates  that  during  the 
deposition  of  the  visible  portion  of  the  lower  sedimentary  formation  the 
water  did  not  fall  more  than  200  feet  below  the  Bonneville  horizon,  and  that 
during  the  period  represented  by  the  upper  deposit  the  water  did  not  fall 
more  than  150  feet  below  the  Bonneville  horizon;  that  is  to  say,  the  locality 
records  twf)  high  stages  of  the  lake  separated  by  an  epoch  of  lower  water, 
and  [)recludes  the  hypothesis  of  a  larger  number  of  great  oscillations  of 
water  surface  within  t!ie  limits  indicated  by  the  local  deposits. 
MON  I 13 


194  LAKE  BOXNEVILLE. 

UPPER  RIVER  BED  SECTION. 

The  second  locality  ;it  which  the  clay  and  marl  are  separated  by  sub- 
aerial  deposits  is  at  the  Old  River  Bed,  about  five  miles  south  of  the  point 
at  which  the  typical  section  of  the  lake  deposits  was  observed.  The  sedi- 
ments here  lie  about  seventy  feet  higher,  rising  gradually  toward  the 
mountains  and  buttes  between  which  the  River  Bed  passes.  The  numljer 
of  distinct  members  in  the  series  is  greater  than  in  the  northern  part  of  the 
River  Bed,  and  the  relations  are  complicated  by  at  lea.st  one  other  uncom- 
formity.  They  are  exhibited  in  the  map  on  PI.  XXXII  and  in  the  sectional 
diagram.  Fig.  21).  The  letters  designating  formations  are  made  to  correspond 
in  the  two  illustrations. 


Fio.  29.— Tbo  Upper  Eivir  Bod  Section;  running  from  AA  to  Ulf  on  Pl.ite  XXXH. 

f7.  —  Upper  Sand.  .S"G  —  .Second  Gravel,  /y  =  Lower  Sand.  If  =  White  Marl.  FG  ^  First  Gravel.  0=  Yelliiw 
Clay.    Vertical  .scale  greater  than  horizontal. 

On  the  left  or  southwest  bank  of  the  River  Bed,  the  paleozoic  terrane  is 
largely  exposed,  consisting  of  limestones  and  sandstones  or  quartzites,  be- 
lieved to  be  of  Silurian  age,  though  not  yielding  fossils  at  this  precise  point. 
The  structure  of  the  mass  is  not  essential  to  the  Pleistocene  history.  On 
the  opposite  side  of  the  River  Bed  are  five  small  buttes  of  trachyte  and 
l)itchstone,  nearly  buried  by  the  later  deposits.  These  are  so  ancient  and 
worn  that  their  forms  convey  no  information  as  to  the  original  extent  of  the 
masses  from  wliich  they  have  been  carved. 

Yellow  ciay.-The  lowest  member  of  the  later  series  of  formations  is  a  fine 
laminated  clay,  which  rests-against  the  Silurian  wall  on  the  side  of  the  River 
Bed,  and  presumably  surrounds  the  bases  of  the  buttes,  although  its  contact 
is  not  seen.  Tliis  is  olive  on  fracture  and  yellow  on  weathered  surfaces, 
and  is  visil)ly  continuous  witli  tlio  Yellow  (*hn'  of  tlic  tv])e  .sectiim. 

First  Gravel.- Resting  on  the  clav,  with  a  sliglit  uncont'oniiity  by  erosion, 
are  several  masses  of  gravel.  The  largest  runs  southward  from  the  more 
southerly  buttes,  and  has  protected  the  underlying  clay  from  erosion.     It  is 


U  S.JEOLCOICAL    SUF'/EY 


hAl<£   B'jHHE\aLLE      PL.  XX>II 


I    c     I      )?//,.»  riav 


0  LI)  inVER    BE  D,    U  TAH 


Topo^rn-phy      hv      W     D     Johns* 


!()-  t'i't't     CoiKoiLlS 


.Iiil.u.H  Hicn  ^Vo.Uih 


Ur.iiwu  hv  li.TbtimpKf 


UPPER  RIVER  BED  SECTION.  195 

lenticuliir  in  cross-section,  and  has  a  niaxinmni  tliickness  of  fifty  feet.  Its 
pjbbles  are  well  rounded,  and  are  relatively  small  at  bottom,  but  at  top 
include  boulders  six  inches  in  diameter.  Near  the  surface  there  is  in  places 
a  calcareous  cement,  binding  the  pebbles  together;  and  there  are  also  rosettes 
or  mushroom-like  masses  of  calcareous  tufa.  The  majority  of  the  pebbles 
are  of  pitchstone  and  trachyte,  similar  to  the  material  of  the  adjacent  buttes, 
but  there  are  also  examples  of  other  volcanic  nicks  not  known  to  occur  in 
situ  within  several  miles,  and  also,  limestone  and  ([uartzite,  such  as  constitute 
the  mountain  ranges  on  both  sides  and  are  distributed  through  all  the  large 
alluvial  cones  of  the  neighborhood.  At  the  west  margin  the  mass  can  be 
seen  to  terminate  in  a  wedge  separating  the  Yellow  Cla}'  from  the  next 
member  of  the  series,  and  beyond  the  limit  of  the  mass  there  is  a  ribbon  of 
sand,  witli  occasional  pebbles,  marking  its  horizon.  Half  a  mile  farther  west 
this  ribbon  expands  into  a  l)ed  of  cciarse  sand  and  gravel,  four  or  five  feet  in 
thickness,  and  half  a  mile  north  there  is  an  independent  outcrop  of  similar 
material  at  the  same  horizon.  These  masses  are  not  of  subaqueous  deposi- 
tion. The  form  of  the  one  first  described,  the  associated  tufa,  and  the  pre- 
ponderance of  boulders  of  local  derivation,  indicate  shore  action,  but  it  is 
possible  that  an  interlacustrine  river  was  the  agent  of  transportation.  What- 
ever their  origin,  the  gravels  mark  a  period  when  the  lake  level  \\as  much 
lovv-er  than  during  the  deposition  either  of  the  Yellow  Clay  or  of  the  suc- 
ceeding deposit. 

White  Marl—Next  lu  ordcr  is  a  bed  of  Avhite  marl,  eight  feet  in  thickness, 
deposited  uniformly  over  the  undulating  surface  of  the  gravel  and  clay  This 
is  in  visible  continuity  with  the  White  Marl  of  the  type  section 

Lower sand-Tlic  uiarl  graduatcs  upward  into  a  bed  of  sand,  fine  below 
and  coarse  above,  with  a  total  de})th  of  45  feet.  The  sand  and  marl  are 
conformable  throughout,  but  were  both  eroded  before  the  deposition  of  the 
next  bed. 

Second  Gravel.- Above  tlic  saud  is  a  second  gravel,  which  rests  unconforma- 
bly  on  the  marl  as  well  as  the  sand,  and  probably  on  the  first  gravel,  from 
which  it  could  not  be  separated  at  the  point  of  contact  Its  pebbles  are 
small  and  are  mingled  with  a  coarse  sand,  the  whole  having  a  thickness  of 
about  two  feet. 


196  LAKE  BONNEVILLE. 

Upper  sand.-Above  the  secoud  jiravel  is  an  up|)t'r  bed  of  sand,  conic )rinal)lo 
with  it  so  far  as  conld  be  ascertained,  but  exhibitinjj;-  little  structure.  This 
has  an  observed  thickness  of  32  feet,  l)ut  may  have  jj^ained  or  lost  by  the 
action  of  the  wind,  wliich  throws  its  surface  into  waves,  and  has  ciiused  it 
to  bury  at  the  north  the  exposure  of  tlic  lower  formations. 

Upper  Gravei.-Finally,  tlierc  appears  about  the  bases  of  the  more  northerly 
buttes  a  fine  gravel  of  alluvial  habit.  It  rests  on  the  second  gravel;  l)ut  its 
relation  to  the  upper  sand  Avas  not  seen. 

On  the  opposite  side  of  the  River  Bed  there  are  a  few  remnants  of  the 
White  Marl  capping  the  Yellow  Clay;  and  at  one  point  a  small  tract  of 
sand  appears,  which  may  belong  either  to  the  lower  or  upper  series. 

In  terms  of  lake  oscillation,  this  section  bears  the  following  interpreta- 
tion; first,  an  epoch  of  deep  submergence,  during  which  the  Yellow  Clay 
was  deposited;  second,  an  epoch  of  emergence,  during  which  the  surface  of 
the  Yellow  Clay  was  slightly  eroded  and  the  first  gravel  was  deposited, 
either  by  Avave  action  or  by  running  water;  third,  a  second  epoch  of  deep 
submergence,  during  which  the  White  Marl  was  thrown  down;  fourth,  a 
continuance  of  submergence,  but  with  a  less  depth,  during  the  deposition  of 
the  lower  sand;  fifth,  a  second  epoch  of  emei'gence,  during  AA'hich  the  lower 
sand  and  White  Marl  were  eroded  and  the  second  gravel  was  deposited; 
sixth,  a  third  submergence,  permitting  the  accumulation  of  the  upper  sand 
as  a  shallow-water  deposit;  seventh,  the  final  emergence  and  tlie  erosion  of 
the  River  Bed.  The  locality  has  thus  been  three  times  submerged  and  as 
many  times  laid  bare  and  subjected  to  atmospheric  erosion. 

It  will  be  convenient  to  refer  to  this  locality  as  the  Upper  River  Bed. 
It  is  coimected  by  continuous  outcrop  with  th(>  Lower  River  Bed,  where 
the  type  section  of  thc^  lake  sediments  is  exhibited;  but  there  is  no  such 
connection  with  Lemington,  forty  miles  away.  It  is  al)out  sevent}'  feet 
higher  than  the  Lower  River  Bed,  and  about  4r)()  feet  lower  than  Lemington. 

OSCILIjATIONS  of  AVATEIl   LKTEL,. 

At  the  Lower  River  Bed  locality  two  emergences  are  recorded;  at 
the  Upper  River  Bed,  three;  at  Lemington,  two;  ;uid  it  is  imjiortant  to  the 
determination  of  the  history  of  the  oscillation  that  the  relations  of  these 
several  emergences  be  ascertained. 


COMBINING  THE  RECORDS.  197 

There  can  l)e  no  error  in  referrin<>'  tlie  latest  of  tlio  indicated  emer- 
gences at  each  of  the  three  locaHties  to  tlie  final  subsidence  of  tlie  lake  a,nd 
desiccation  of  the  basin.  There  were,  of  course,  intervals  between  the 
appearances  of  the  several  localities,  tlie  hig'hest  being  first  exposed  by  the 
receding  water,  but  the  existence  of  these  intervals  does  not  contravene  the 
general  fact.  We  may  therefore  restrict  our  attention  to  the  temporary 
emergences,  of  which  the  Upper  River  Bed  witnessed  two  and  the  other 
localities  one  each.  Continuity  of  outcrop  demonstrates  the  identity  of  the 
first  emergence  at  the  Upper  River  Bed  with  the  emergence  recorded  at  the 
Lower  River  Bed;  and  there  is  stratigraphic  evidence  of  a  cumulative  na- 
ture in  favor  of  correlating  the  Lemington  emergence  with  these  two.  8ince 
this  is  not  direct  and  positive,  it  is  necessary  to  state  it  somewhat  fully,  in 
order  to  exhibit  the  weakness  of  the  argument  as  well  as  its  strength. 

The  temporary  emergence  is  recorded  at  the  Lower  River  Bed  by  an 
unconformity — by  the  erosion  of  the  surface  of  the  Yellow  Clay  before  the 
deposition  of  the  White  Marl.  The  section  includes  in  descending  order: 
(1.)  White  Marl,  crowded  with  shells  at  the  base;  (2.)  Unconformity; 
(3.)  Yellow  Clay.  All  the  elements  of  this  section  are  traceable  continu- 
ously to  the  Upper  River  Bed  locality,  and  they  are  repeated  at  several 
other  localities  low  down  in  the  basin.  A  few  of  these  are  higher  on  the 
slopes  of  the  basin  than  the  Upper  River  Bed,  and  one  attains  an  altitude 
of  250  feet  above  the  latter  locality,  falling  only  200  feet  short  of  the  Le- 
mington locality.  The  unconformity  may  therefore  be  said  to  have  been 
traced  by  a  harmonious  series  of  observations  within  200  feet  of  the  level 
of  the  Lemington  locality.  At  Lemington  the  stratigraphic  series  is  com- 
parable, but  not  identical.  It  contains  all  the  enumerated  elements  except 
the  White  Marl,  and  this  is  replaced  by  a  white  clay.  On  the  other  hand, 
the  second  emergence  recorded  at  the  Upper  River  Bed  has  not  been  recog- 
nized elsewhere,  so  that  there  is  some  warrant  for  the  belief  that  the  oscil- 
lation of  lake  surface  causing  it  had  not  a  great  amplitude.  Finally,  the 
sediment  recording  the  latest  submergence  at  the  Upper  River  Bed  is  a  sand 
merely,  indicating  that  the  depth  of  the  water  was  not  great;  and  if  this 
submergence  did  not  include  the  Lemington  locality,  the  preceding  emerg- 
ence, as  recorded  at  the  River  Bed,  could  in  no  manner  be  separated,  at 
Lemington,  from  the  final  emergence. 


198 


LAKE  BONNEVILLE. 


The  accompanying'  diagram,  Fig.  30,  expresses  graphically  the  con- 
clusions reached  from  the  joint  consideration  of  tlui  threes  localities.  The 
vertical  scale  represents  heiglit  of  water  surface,  ranging  from  tlic  level 
of  Great  Salt  Lake  to  that  of  the  Bonneville  shore.  The  horizontal  scale 
represents  (from  left  to  right)  the  oi-der  of  sequence,  but  witlioiit  any 
attempt  to  exjjress  the  relative   duration  of  the  several  elements   of   the 


UPP£RRIV£RBU 
LOWtlililVtnBEl) 


Fig.  30. — Diagram  ut'  Lake  Of^cillatiuas  uil'enud  fium  Deposits  aod  Erosion)'. 

history.  The  curve  exhibits  the  progressive  rise  and  fall  of  the  lake. 
Beginning  at  the  left,  we  have  high  water  represented  by  the  Yellow  (Jlay 
at  all  three  localities,  then  an  ei)oc]i  of  low  water  represented  by  the  allu- 
vium at  Lemington,  by  the  first  gravel  at  the  Upper  River  Bed,  and  l)y 
unconformity  at  the  Lower  River  Bed.  llow  low  the  water  fell,  does  not 
appear.  8o  far  as  this  evidence  goes,  it  niay  have  fallen  only  to  the  bottom 
of  the  Old  River  Bed,  or  it  niay  have  descended  to  the  level  of  Great  Salt 
Lake,  or  even  lower.  Then  came  a  second  and  shorter  epoch  of  deep  water, 
represented  at  Lemington  by  white  chu-  and  sand,  nt  tlie  Tpper  River  Bed 
locality  by  the  White  Marl  and  the  lower  sand,  and  at  the  Lowei-  River  Bed 
by  the  White  Marl.  The  final  emergence  is  recorded  at  Lemington  by  the 
superficial  alluvium  and  by  the  erosion  of  the  modem  cliannel  of  the  Sevier 
River.  Tt  is  recorded  at  the  Lower  River  Bed  by  the  erosion  of  the  River 
Bed  and  l)v  its  ])artial  filling  with  alluvimn.      .Vt  the   Upper  River  Bed  the 


THE  TWO  FLOODS  COMPARED.  199 

second  and  third  gravels,  witli  the  intervening  sand,  record  a  general  de- 
scent of  the  water,  interrupted  by  i'n  n})ward  movement  of  small  extent. 

It  is  not  to  be  understood  that  this  curve  exhibits  any  more  of  the 
historj^  of  oscillation  than  is  derivable  from  the  deposits  and  unconformities 
at  these  three  localities.  The  additional  elements  derived  from  the  study  of 
the  shore-lines  are  purposely  ignored,  and  innumerable  minor  oscillations 
are  perforce  omitted.  If  sections  of  all  the  alluvial,  littoral,  and  lacustrine 
deposits  of  the  basin  were  accessible;  and  if  these  were  elaborately  studied, 
it  can  not  ]k'  doubted  that  the  simi>le  curves  here  drawn  to  represent  the 
two  great  submergences  of  the  basin  would  have  to  be  replaced  by  lines 
with  innumerable  small  inflecti(ms,  similar  to  that  deduced  from  the  upper 
deposits  at  the  Upper  River  Bed.  In  the  sequel  the  data  embodied  in  this 
curve  will  be  combined  with  other  data  in  our  possession,  including  that 
from  the  shore-lines  and  outlet,  and  a  more  accurate  curve  will  be  drawn. 

HEIGHT  OF  THE  FIRST  MAXIMUM. 

If  the  first  submergence  had  been  carried  so  far  as  to  produce  outflow, 
the  corrasion  of  the  channel  of  outflow  would  have  made  it  impossible  for 
the  second  submergence  to  extend  higher  than  the  Provo  level.  Knowing, 
as  we  do  from  tlie  phenomena  of  the  shores  and  the  features  of  Red  Rock 
Pass,  that  the  second  submergence  was  characterized  by  outflow,  we  are 
warranted  in  concluding  that  the  first  rise  was  somewhat  less  tluni  tlie  sec- 
oiul.  The  amount  of  tlu*  difference  appears  to  be  indicated  by  the  embank- 
ments of  Preuss  \alle}',  to  which  allusion  has  aln^ady  been  made.  At  the 
north  group  of  embankments,  figured  in  PI.  XVI,  there  is  an  older  series 
j)artly  buried  l)v  a  newer;  and  the  hig'hest  mend^er  of  this  lies  90  feet  below 
tlie  Boimeville  horizon.  It  is  probable  that  this  represents  the  extreme 
advance  of  the  earlier  flood. 

At  the  Leming-ton  locality  the  Bonneville  shore-line  is  the  only  one 
represented  by  a  sea-clifl"  and  ten-ace;  but  at  lower  levels  there  are  lines 
of  tufa  adhering  to  tlie  (juartzite  and  apparently  marking  temporary  positions 
of  the  water  level.  Probably  the  relation  of  the  waves  to  the  contiguous 
slopes  enabled  them  to  employ  shore  drift  in  attacking  the  mountain  face  at 
the  Bonneville   horizon,  l)ut  did  not  afford  them   that  aid   at  lower  levels. 


200  LAKE  BONNEVILLE. 

Tlie  unarmed  waves  not  only  were  unable  to  tear  down  the  cliff,  l)ut  were 
compelled  by  their  peculiar  chemical  constitution  to  add  a  iiiiiici-al  cdatino- 
to  its  face.  These  lines  of  tufa  are  all  covered  l»y  tli(!  lacustrine  deposits 
except  where  exposed  by  recent  denudation;  and  it  is  assumed  that  certain 
of  them  now  buried  by  the  White  Marl  l)eds  were  formed  durin<>-  tin-  d('])o- 
sition  of  some  portion  of  the  Yellow  Clay.  The  ]iiji,liest  of  tliesc;  is  se])arated 
from  the  Bonneville  shore-line  by  an  interspace  of  90  feet  (aneroid  mea- 
surement). 

THE  WHITENESS  OF  THE  WHITE  MARL. 

As  soon  as  the  wide  distribution  of  the  White  Marl  and  the  Yellow  Clay 
and  the  constancy  of  their  contrast  came  to  be  appreciated,  attention  was 
directed  to  the  determination  of  the  cause  of  their  difference.  It  is  easy  to 
luiderstand  a  gradation  in  texture  and  composition  of  strata  as  one  passes 
from  the  margin  of  a,  l)asin  toward  its  center,  or  from  the  vicinity  of  sea- 
clitfs  and  river  mouths,  where  the  supply  of  detritus  is  great,  to  quieter  and 
remoter  places,  reached  only  by  sediment  long  held  in  suspension;  but  it  is 
not  so  easy  to  understand  why  there  should  be  an  abrupt  change  in  the 
sedimentary  sequence  throughout  an  entire  basin.  If  the  true  explanation 
of  the  difference  between  these  strata  can  be  reached,  it  should  contribute 
something  to  the  history  of  the  lake.  For  the  purpose  of  seeking  such  an 
explanation,  the  character  of  the  two  deposits  has  been  examined  Ixith  chem- 
icallv  and  microscopically.  Two  samples  each  of  the  White  ]\Iarl  and  Yel- 
low Clay  were  analyzed  by  Prof.  0.  D.  Allen  of  New  Haven,  with  the 
results  exhibited  in  Table  III. 


CHEMICAL  COMPOSITION  OF  THE  CLAY  AND  THE  MARL.      201 


Table  III. — Jnali/ses  of  Bonneville  Setii, 


inents. 


I.  White  Marl  from  the  Ohl  River  Beii. 
n.  White  M.-111  IVo.u  ne.ir  Willow  SpriuR,  .it  the  eastern  h.i30  of  the  Deep  Creek  Mouutiins. 

III.  Upper  part  of  Yellow  Clay,  Old  Kiver  Bed. 

IV.  Lower  part  of  Yellow  Clay.  Ohl  River  lied. 


lusoluble;  percentage    

Soluble;  percentage 

100  parts  of  the  Insoluble  portion  coutain- 

Silica    

Aluiuiua  

Ferric  o.xide 

Potaaaa 

Soda 

Lime 

Magnesia   

Carbon  dioxide    


Water  . 


100  parts  of  the  determined;  Soluble  constitueut.s  eoutaiu- 

Sulphiiric  oxide 

Lime  ■ 

Magnesium 

Potash  

Soda 

Sodium  oxide**  

Chlorine 

Nitric  acid** 

Boric  acid-  

Carbonic  acid 

Lithium 


4.5.  03 
8.03 
2.«5 
1.70 
.68 

19.08 
2.71 

16.25 

2.33 


Oxygen  equivalent  to  chlorine. 


90.32 

23.  539 
.916 
1  U« 
.534 

47.  039 


96.84 
3.16 

23.  05 

3.20 

1.10 

.70 

.54 

3  i.  08 

2.87 

31.49 

1.23 


33. 857 
tr'ace 
trace 
trace 


20.  204 

8.9i;6 

.721 

1.363 

39.  295 


Probable  couibination  of  soluble  ciuiaJiruents- 

Calcium  snlphato 

Magnesium  sulphate  

Pota-siuni  sulphate 

Sodium  sulphate 

Calcium  chloride 

Magnesium  chloride 

Potassium  chloride 

Sodium  chloride    

Sodium  oxide** 


107.  633 
7.633 


100.  000 


2.225 

3.444 

.987 

36.  079 


38.  029 
trace 


III. 


0.71 

43.84 

13.85 

4.04 

2.40 

.44 

12.43 
4.54 

11.88 
2.84* 
4.111 


lY. 


100.43 


8.806 
2.341 
5.980 
1.792 
50.  742 


95.  57 
4.43 

41.74 

13.00 
3.61 
1.87 
.70 

16.01 
4.96 

15.78 

3.78 
100.45 


39. 169 
present 


2.045 
4.322 
1.897 
.370 
50.  637 


52.  594 
Iiresent 


108.578  1 
8.  .578  I 


108.  836 
8.836 


100.  000  I     100.  000 


56.  789 
1.476 


100. 000 


21.  775 
2.163 
2.521 
8.  .51 1 


5.685 
8.193 


62.  659 
2.371 


111.865 
11.865 


100.  000 


7.729 

2.835 

52.  830 

22. 728 


100.  UOO 


5.727 

3.759 

.586 

76.  336 

10.115 


100.  000 


*  Water  lost  at  100°  C. 
t  Water  lost  liy  ignition 
J  The  total  wei-bt 

chloride  would  be  th 

tions  of  the  solution. 

stitueuts  were  delerm 


por- 
con- 


♦.„      "The  sodium  oxide  reported  among  the  constituents" is  not  ass'imed  to  be  free,  but  to  exist   as  sodium  oitrntp 
*:i^Ll ",'  yi':?."j'_.'T:'»  f^^'V"  e.'ol' '"Stance;  and  in  the  c;,se  of  the  thir.l  and  fourth'  santnles  it"anto,,nt'  L' c  '  »;  t^'f: 


^^ii^^Ss^^kfsr- '^-'^ --'^^^  '*-«^^-  ^^^>^^^^^:^\:'iS'o}  ^^:^ 


202 


LAKE  BONNEVILLE. 


The  soluble  constituents  need  not  concta-n  us  at  present,  for  they  do 
not  materially  affect  the  color  of  the  beds.  Indeed  the  characteristic  colors 
are  everywhere  recognized  by  the  weathered-  surfaces,  from  which  the  solu- 
ble materials  are  nearly  or  completely  leached.  Tlie  carbonic  acid  in  each 
of  the  samples  is  nearly  sufficient  to  sati.sfy  the  lime  and  magnesia;  and  it 
maybe  assumed  to  have  been  all  combined  with  tliose  bases.  The  alumina, 
iron,  soda,  and  the  remaining  lime  and  magnesia,  undoubtedly  exist  in  the 
form  of  silicates,  while  the  unsatisfied  silica  is  free.  The  microscopic 
characters  indicate  that  the  silicates  are  chiefly  feldspars;  and  if  we  assume 
orthoclase  to  be  predominate,  the  bases  are  barely  satisfied  in  the  case  of 
one  sample  and  there  i^  an  excess  of  silica  in  each  of  the  others.  It  is  prob- 
able that  the  following  table  represents  the  constitution  of  the  earths  nearly 
enough  for  the  purposes  of  the  present  discussion. 

Table  IV.— Condensed  Results  of  Analyses  in  Table  III. 


Sample 

Sample 
II. 

Sample 
III. 

Sample 

White 

Marl: 

Mean  uf 

1  and  II. 

Yellow 

Clay: 

Mean  of 

III  and  IV. 

Carbonates  of  lime  and  magnesia-  - 
Silicates 

Per  cent. 
36 
54 
10 

Per  cent. 
70 
18 

12 

Per  cent. 
26 

74 
0 

Percent. 
34 
62 

*        1 

Per  cent. 
53 
36 

n 

Per  cent. 
30 

68 
2 

Free  Silica , 

Totals 

100 

100 

100 

100 

100 

iOO 

Under  the  microscope  the  White  Marl  is  seen  to  contain,  first,  numerous 
minute  crystals  exhibiting  double  refraction;  second,  minute  particles,  ap- 
parently clastic,  likewise  doubly  refracting;  third,  siliceous  organisms.  The 
crystals  are  too  snuill  for  meiisureinent.  They  appear  in  gencrMl  to  be 
taj)ering  pyramids  whose  longer  diameters  are  three  or  four  times  their 
shorter.  They  undoubtedly  represent  the  carbonates.  The  clastic  matter 
is  conceived  to  represent,  in  like  manner,  the  silicates,  and  possil)h-  ;i  portion 
of  the  free  silica.  The  remainder  of  the  silica,  or  })ossil)ly  th(^  whole  of  it, 
is  contained  in  tlie  microscopic  organisms.  These  are  ])artly  diatoinaceous, 
but  include  also  numerous  slender  tubes  witli  punctate  or  jJiipilkite  walls 
which  may  be  spiculae  of  sponges. 

Unfortunately,  a  majority  of  the  samples  of  Yellow  Clay  which  should 
have  been  examined  for  comparative  purposes,  were  lost  in  transportation 


CARBONATES  VERSUS  SILICATES.  203 

before  tlio  microscope  was  applied  to  them  The  only  two  })reserved  are 
from  a  subhttoral  deposit  at  Lemingtou  and  from  the  type  section  in  the 
Old  River  Bed.  These  exhibit  only  rounded  grains  of  crystalline  matter, 
for  the  most  part  clear,  uncolored,  and  doubly  refracting-.  Neither  diatoms 
nor  cr}'stals  were  discovered. 

In  brief,  the  White  Marl  and  Yellow  Clay  resemble  each  other  in  com- 
position, but  the  former  is  characterized  by  a  relatively  great  amount  of 
earthy  carbonates  and  by  free  silica,  while  in  the  latter  the  argillaceous 
element  predominates.  In  the  former  the  carbonates  were  largely  thrown 
down  as  a  chemical  precipitate,  and  St  least  a  portion  of  the  silica  is  an 
organic  precipitate.  The  whiteness  of  the  marl  appears  to  be  largely  due 
to  its  precipitated  elements. 

These  differences  in  the  characters  of  the  two  deposits  were  unques- 
tionably determined  by  some  event  in  the  history  of  the  lake;  during  the 
intervening  epoch  of  low  water  the  conditions  of  sedimentation  underwent 
some  change.  A  double  interest  attaches  to  the  determination  f)f  the  nature 
of  this  change;  on  the  one  hand  its  discovery  would  add  an  element  to  the 
history  of  the  lake;  and  on  the  other  it  might  lead  to  the  establishment  of 
some  law  of  sedimentation  hitherto  unrecognized.  Much  thought  has  there- 
fore been  given  to  the  subject,  hypotheses  have  been  framed  and  many 
experiments  have  been  made,  but  the  results  of  the  experiments  are  unfor- 
tunately negative,  and  the  j)i'o]>lem  can  not  be  regarded  as  solvcil.  It  is 
necessary,  however,  to  give  some  consideration  in  this  place  to  certain  of 
the  hypotheses  for  the  ])urpose  of  showing  the  grounds  ujjon  which  one  of 
them  was  so  seriously  entertained  as  to  receive  a  provisional  jiublication. 

SOURCE  OF  MATERIAL. 

The  simplest  explanation  of  the  change  in  sedimentation  is  that  the 
nature  of  the  material  supplied  to  the  lake  by  tributary  streams  was  for  some 
reason  different.  In  the  interval  of  time  between  the  two  epochs  of  deposi- 
tion, the  deformation  of  the  earth's  cnist  may  have  wrought  changes  in  the 
area  of  the  basin,  either  cutting  off  some  important  element  of  the  detritid 
contribution  or  making  some  equally  inqiortant  addition.     The  prime  diffi- 


204  LAKE  BONNEVILLE. 

culty  with  tliis  hypothesis  is  that  the  configuration  of  the  region  offers  no 
way  of  rendering  it  h)cal  and  concrete.  The  calcareous  tribute  of  the  basin 
must  flow  chiefly  from  the  limestones  of  the  Wasatch  and  associated  ranges, 
and  the  drainage  system  by  which  it  is  conveyed  seems  to  have  been  estab- 
lished before  the  Pleistocene.  The  possibility  of  an  ancient  modification  in 
the  drainage  system  of  the  Bear  River  will  be  discussed  in  the  next  chapter; 
but  such  modification,  if  it  occurred,  can  not  have  had  so  late  a  date  as  the 
epoch  of  the  White  Marl. 

COMPOSITION  OF  LAKE  WATER. 

A  second  explanation  is  that  the  conditions  of  sedimentation  and  pre- 
cipitation in  the  basin  were  ixiodified  after  the  epoch  of  the  Yellow  Clay  by 
a  change  in  the  mineral  contents  of  the  water  of  the  lake.  It  is  well  known 
that  the  precipitation  of  certain  substances  from  solution  is  favored  by  the 
presence  of  certain  other  substances,  and  by  yet  others  is  retarded.  It  is 
equally  well  known  that  the  fall  of  minute  suspended  particles  is  similarly 
accelerated  by  the  presence  of  various  substances;  and  their  fall  is  probably 
retarded  by  other  substances.  Is  there  any  ground  for  postulating  a  change 
in  the  mineral  contents  of  the  lake  which  would  account  for  the  observed 
change  in  the  natui'e  of  the  deposit? 

There  are  three  different  changes  of  this  sort  readily  conceived.  First, 
the  water  having  been  relatively  pure  during  the  deposition  of  the  Yellow 
Clay,  it  may  have  acquired,  during  the  interval  of  recession,  a  large  amount 
of  mineral  matter,  so  as  to  be  a  brine  at  the  time  of  its  second  flooding. 
Second,  the  water  of  tlie  first  great  lake,  having  been  a  feeble  brine,  may 
have  become  so  concentrated  during  the  epoch  of  low  water  as  to  precipi- 
tate its  less  hygroscopic  minerals,  with  the  result  that,  when  the  second  fiood 
came,  a  mother  liquor  was  diluted  instead  of  the  normal  brine.  Third,  tlie 
water  of  the  first  great  lake,  having  been  a  feeble  brine,  may  have  been  in 
the  interval  not  merely  concentrated  but  completely  evaporated,  the  desic- 
cation product  being  mingled  with  and  buried  by  mechanical  sediments,  so 
as  not  to  be  redissolved  at  the  time  of  the  second  flood.  On  the  first  sup- 
position, the  White  Marl  epoch  was  characterized  by  a  stronger  brine  than 
the  Yellow  Clay  epoch.     On  the  second,  it  was  characterized  by  the  min- 


DID  THE  WATER  CnANGE  IN  COMPOSITION?  205 

erals  pecular  to  mother  liquors.     On  the  third,  it  was  characterized  by  purer 
water. 

Each  of  these  postulated  changes  may  be  supposed  to  have  acted  in 
either  of  two  ways;  first,  the  })eculiar  })roperties  of  the  menstruum  of  the 
second  flood  may  have  caused  the  precipitation  of  an  exceptionally  large 
proportion  of  the  calcareous  matter  in  the  center  of  the  basin,  and  may 
have  determined  the  assumption  of  the  crystalline  form;  second,  its  prop- 
erties may  have  determined  the  precipitation  of  argillaceous  sediment  near 
the  shore,  thereby  diminishing  its  importance  in  the  center  of  the  basin 
and  thus  increasing  the  relative  percentage  of  calcareous  matter.  No  at- 
tempt has  been  made  to  test  the  first  of  these  assumptions  experimentally, 
for  the  reason  tliat  the  natural  reactions  could  not  be  fairly  represented  by 
the  necessarily  rapid  processes  of  the  laboratory.  It  may  be  said,  also,  that 
the  assumption  is  less  accordant  with  what  is  known  of  the  distribution  of 
calcareous  matter  in  the  basin.  From  the  second  point  of  view  a  series  of 
experiments  was  instituted,  the  investigation  being  conducted  by  my  assist- 
ant, Mr.  I.  C.  Russell. 

Experiments.-In  tlic  couduct  of  thcsc  experiments  no  attempt  was  made  to 
discuss  the  general  problem  of  the  properties  of  dissolved  substances  as  the 
precipitants  of  sediments,  but  attention  was  confined,  to  the  specific  problem 
presented  by  the  lake  sediments.  With  the  excej)tion  of  distilled  water,  the 
only  materials  used  were  those  which  occur  in  the  basin  and  are  concerned 
with  the  practical  problem.  The  brine  of  Great  Salt  Lake  in  various  stages 
of  dilution  was  assumed  to  represent  the  water  of  Lake  Bonneville,  the 
diluent  being  in  each  case  the  approximately  fresh  water  of  some  stream 
now  tril)utary  to  Great  Salt  Lake  and  anciently  tributary  to  Lake  Bonneville. 
The  fine  sediment  employed  was  a  sample  of  the  Yellow  Clay.  The  water 
of  the  selected  stream  was  mixed  in  various  proportions  with  the  Ijrine,  and 
ecpial  quantities  of  the  mixtures  were  arranged  in  a  series  of  similar  vessels, 
tlie  pure  stream  water  and  pure  brine  constituting  the  first  and  last  terms 
of  the  series.  Equal  portions  of  the  finely  divided  clay  were  then  added  to 
each  vessel  and  mingled  with  the  water  by  shaking  or  stirring,  after  which 
the  vessels  were  allowed  to  stand  for  several  days  and  notes  were  made  of 
the  relative  rates  of  precipitation. 


206  LAKE  BONNEVILLE. 

The  first,  streuin  water  einj)l()yetl  was  that  of  City  Creek,  the  sample' 
being'  <i;'athei-ed  at  Salt  Lake  City.  The  stream  is  luit  lar<;-e,  l)ut  its  sources 
lie  ainoiii^'  rocks  typical  of  the  region  from  which  tlie  water  suj)[)l\'  ni'  the 
basin  is  derived.  ^I'he  results  were  pronounced  ;iud  apparently  unecjuivocal. 
Tlie  clay  fell  riipidly  in  tlie  watci-  of  the  creek  ;iih1  its  dcpositiuii  was 
indefinitely  delayed'  in  the  l)rine,  and  the  vai-ious  mixtures  <j;;\\v.  a  graded 
series  of  rates  of  sedimentation.  It  seemed  evident  that  a  relatively  fresh 
condition  of  the  ancient  lake  would  favor  the  rapid  precipitation  of  mechan- 
ical sediment,  would  thus  accumulate  it  close  to  the  shore,  and  would  leave 
the  calcareous  or  chemical  ]n'ecipitates  in  relative  preponderance  near  the 
center  of  the  Ijasin.  Tiie  provisional  conclusion  followed  that  the  cixkIi  of 
the  White  Marl  was  characterized  l)y  relatively  fresh  water,  and  this  was 
published  in  a,  })reliminary  presentation  of  the  investigation.^ 

It  was  afterwards  learned  that  the  experiments  of  Ramsey,  Brewer,  and 
others  had  demonstrated  the  potency  of  minute  traces  of  certain  suhstnuces 
as  precipitants  of  sediment;  and  it  became  evident  that  in  order  to  \-erify 
the  results  of  the  e.x})eriments  with  the  water  of  City  Creek,  it  would  be 
necessary  to  employ  waters  representative  of  a  larger  share  of  the  su])ply 
of  the  liasin.  Samples  were  accoixlingly  obtained  from  Utah  Lake,  the  ijrin- 
ci])al  source  of  the  Jordan  River,  and  from  the  Bear  River  at  Evanston. 
Each  of  these  sam[)les  represents  about  one-third  of  tlie  snpplv  of  (ireat 
Salt  Lake;  and  they  may  fairly  l)e  assumed  to  tyi)ifS'  tlu^  fVesh-\\  atei-  streams 
of  the  basin.  Each  was  subjected  to  a  series  of  experiments  similar  tn  those 
arranged  for  City  Creek  water.  The  sample  from  ITtah  Lake  yielded 
identical  results.  With  the  sample  from  Bear  River  the  results  were  dif- 
ferent; it  was  found  that  the  clay  was  precipitated  with  espial  rapidit\-  from 
Bear  River  water,  from  the  brine  of  Great  Salt  Lake,  and  from  all  luixtiires 
of  the  two.  It  is  evident,  therefore,  that  City  Creek  watei-  is  not  in  this 
respect  a  true  representative  of  the  entire  fresh-water  tribute  of  the  basin; 

'  It  is  not  to  be  supposed  that  the  sodium  chloride  and  other  mineral  constituents  of  the  Salt  Lake 
hrlae  retard  the  precipitation  of  sediments.  The  experiments  show  merely  that  they  promote  it  less 
than  the  miner.il  constituents  of  the  City  Creek  water.  That  tliey  actually  imimole  it,  was  demon- 
strated by  coni|>arative  experiments  witli  distilled  water.  Salt  Lake  brine  and  distilled  water  ai;ree  in 
retaininrj  a  residuary  milkiuess  for  an  indefinite  period,  but  the  approximate  clearing  of  the  brine  is  by 
far  the  more  rapid. 

'Second  Ann.  Kept.  U.  S.  Geol.  Survey,  pp.  177-180 


EXPERIMENTS  IN  SEDIMENTATION. 


207 


and  while  the  experiments  with  Bear  River  water  do  not  negative  the  theory 
broached  in  the  i)reliniinary  pubUcation,  they  serionwly  weaken  its  snpport. 
It  is  a  cnrions  fact  that  the  City  Creek  and  Utah  Lake  waters,  having 
simihxr  jn'operties  as  precipitants,  yet  diflfer  widely  in  their  mineral  constit- 
uents ;  and  that  the  water  of  Bear  River,  while  behaving  very  difterently  as 
a  precipitant,  yet  closely  resembles  in  constitution  that  of  City  Creek.  The 
accompanying  table  of  analyses  (Table  V.)  shows  that  the  water  of  Utah 
Lake  is  characterized  by  the  sulphate  of  lime,  while  the  waters  of  City  Creek 
and  Bear  River  are  characterized  by  the  carbonate. 

Table  V.  Mineral  Contents  of  Fresh  Waters  in  the  Salt  Lake  Basin. 

I.  Water  of  City  Creek,  taken  at  head  of  Main  .Street,  Salt  Lake  City,  December  3(1,  1883. 
II.  Water  of  Bear  Hirer,  taken  at  Evan.ston,  Wyoming. 
III.  Water  of  Utah  Lake,  taken  Deeember,  1883. 

[t.  analyzeil  -jy  T.  M.  Chatardi  11  anil  III,  by  F.  VV.  Clarke.] 


Grams  to  tbe  litre. 

Per  cent,  of  total  solids. 

I. 

n. 

III. 

I. 

II. 

III. 

Calcium 

.0589 
.0174 
.0091 
.  1280 
.0070 
.0131 
.0010 
.0090 

.  0432 
.  0125 
.  0082 
.  0982* 
.0105 
.0049 

.  0.-.58 

.OIKC 
.0178 
. 0008* 
.  1300 
.0124 

24.19 
7.15 
3.74 

52.  57 
2.87 
5.38 
0.41 
3.69 

23.41 
6.78 
4.44 

53.24* 
5.09 
2.65 

18.24 
6.08 
5.81 

19.  88* 

42.68 

4.04 

Snlplmric  Acid 

Silica 

.0070 

.0100 

3.79 

3.27 

.2435 

.1845 

.3060 

100.  00 

100.  00 

100.00 

PEOBABLE  COMBINATION. 


Calcium  Carbonate 

Magnesium  Carbonate 

Sodium  Carbonate 

.  1400 
.0606 
.0014 
.0099 

.1080 
.0438 

.0038 
.0644 
.0204 
.1849 

.0204 



.0100 

57.49 
24.88 
0.57 
4.07 

8.87 
0.42 
3.70 

59.20 
24.01 

1.25 
21.19 

6.71 
60.84 

6.71 

.0135 
.0081 

.0070 

8.48 
4.49 

Sodium  Chloride 

.0216 
.0010 
.0090 

Silica 

3.82 

3.30 

.2435 

.  1824            . 3039 

100.  00 

100.  Oil 

100.00 

"Estimated  by  difference. 

The  postulate  that  the  second  flood  diluted  a  brine  which  by  fractional 
preci})itation  had  accjuired  the  character  of  a* mother  liquor,  was  tested  in 
the  following  manner:  Samples  of  the  brine  of  Great  Salt  Lake  were  evap- 
orated until  various  portions  of  the  saline  contents  had  been  precipitated, 


208  LIKE  BONNEVILLE. 

and  tlic  residuiu-)-  licjuurs  were  tlien  diluted  with  distilled  water  and  coni- 
pared  with  similar  dilutions  of  the  Salt  Lake  l)riiie.  It  was  found  tluit  sedi- 
ment sejjarated  with  eijual  rapidity  from  the  lirine  juid  the  motlicr  liiiuors; 
and  parallel  results  were  obtained  tVom  their  corresponding  derivatives. 

The  only  one,  then,  of  the  alternative  hyj)otheses  suggested  above 
which  tinds  any  support  in  the  experimental  results  is  the  one  of  wliich  pub- 
lication has  l)een  already  made,  and  the  support  accorded  it  is  insutticient 
to  inspire  confidence.  If  the  water  of  Bear  River  instead  of  City  Creek  had 
l)een  first  subjected  to  experiment,  the  theory  would  have  been  at  once 
abandoned.  Nevertheless,  since  it  is  not  controverted  by  the  experiments, 
and  since  it  has  practically  no  competitor,  it  is  proper  that  its  relation  to 
the  general  question  of  lake  history  be  fully  set  forth. 

DEPOSITION   BY  DESICCATION. 

Fully  stated,  it  takes  the  following  form.  During  the  first  rise  of  the 
lake,  or  at  least  during  that  part  of  it  represented  by  the  visible  portion  of 
the  Yellow  Clay,  the  saline  matter  was  held  in  solution  in  such  })roportioii 
that  tlie  precipitation  of  mechanical  sediment  was  slow.  The  clay  intro- 
duced by  the  streams  and  by  the  undertow  remained  in  suspension  a  long 
time,  and  was  therefore  widely  distributed,  covering  the  whole  Ixtttom  of 
the  liasin.  At  tlie  close  of  the  Yellow  Clay  epoch  the  liasin  was  completely 
desiccated,  the  saline  matter  l)eing  gathered  in  the  lowest  depression  and 
there  precipitated.  The  raiiifiill  of  the  basin,  however,  <lid  not  iliniiiiisii  to 
absolute  zero,  and  occasional  Hoods  washed  detritus  into  the  (le])ression 
containing  the  salt,  until  the  lattei-  was  either  covered  or  intermingle(l  with 
mechanical  sediment,  and  in  either  case  effectually  buried.  It  w;is  never 
redissolved,  and  when  the  increase  of  the  streams  caused  the  basin  to  be 
refiooded,  the  water  of  the  new  lake  was  almost  as  fresh  as  tlie  stre;nus.  It 
had  the  property  of  throwing  down  suspended  clay  with  great  i-apidity,  so 
that  tlu^  greater  part  of  the  nuid  brought  to  it  by  the  .streams  was  de|)osited 
near  th(^  shore,  and  chemical  and  organic  precij)itates  ac(piired  relative  im- 
portance in  the  center  of  the  l)asin. 

It  is  j)roper  to  add  tliat  tiie  process  of  burial  by  <lesiccation,  here 
invoked  to  account  for  the  disappearance  of  saline  matter,  is  not  liv])othetic, 


WATER  FRESHENED  BY  DESICCATION.  209 

except  as  regards  tlie  particular  application.  It  has  been  full}-  demonstrated, 
especially  by  the  investigations  of  Russell/  <^hat  it  is  an  actual  process,  all 
stages  of  which  are  exhibited  in  the  modern  history  of  the  small  basins  of 
Utali  nud  Nevada.  Not  only  are  soluble  salts  found  mingled  with  the  earths 
of  tlic  plavas  in  all  proportions,  but  crystalline  lavers  have  been  discovered 
bcncatli  eart]i\-  })la\a  dei)osits;  and  there  are  numerous  modern  lakes  of 
feeble  salinitv  occupying  closed  basins  whose  upper  slopes  are  covered  by 
saliferous  lacustrine  deposits  of  earlier  origin,  and  whose  salts  have  never 
been  discharged  by  means  of  a  lake  outlet. 

It  is  an  essential  part  of  the  hvpothesis  that  the  lake  was  evaporated 
to  (Irvness  after  the  deposition  of  the  Yellow  Clay;  and  the  establishment 
of  tlie  hvi)0thesis  would  demonstrate  an  element  of  the  curve  of  oscillation 
for  which  there  is  no  other  evidence. 

ORGANIC   REMAINS. 

The  fossil  remains  yielded  most  alntndantly  by  the  Bonneville  beds  are 
tests  of  fresh-water  univalve  mollnsks.  These  are  found  at  all  horizons  in 
the  lacustrine  deposits,  and  are  likewise  imbedded  in  the  tufa,  l^hey  are 
best  preserved  in  the  White  Marl,  and  are  especially  abundant  at  the  base 
and  the  summit  of  that  member.  The  specimens  preserved  in  the  Yellow 
Clay  are  fragile,  usually  crumbling  on  exposure  to  the  air,  and  only  in  rare 
instances  washing  out  so  as  to  be  found  entire  on  the  siirface.  Those  at  the 
base  of  the  White  Marl  are  firm,  but  of  light  weight  and  lusterless,  as  though 
completely  despoiled  of  their  organic  matter.  Those  at  the  top  of  the  Marl, 
lying  free  upon  the  surface  of  the  desert,  are  still  dense  and  brilliant,  though 
completely  bleached.  They  evidently  belong  to  the  epoch  in  which  the 
lake  was  finally  shrinking. 

The  first  armouncement  of  these  mollusca  was  by  Hayden,  who  made 
a  small  collection  in  1870,  publishing  an  account  of  it  in  his  annual  report 
for  that  year.^  An  earlier  observation  was  made  by  Engelmann  in  1859, 
but  his  report  remained  unpublished  luitil  1876.' 

'  Geological  History  of  Lake  Lahontan,  pp.  81-86,  224-230. 
2U.  S.  Geol.  Survey  of  Wyoiiiiug,  1870,  p.  170. 

'Exploratious  across  the  Great  Basin  of  Utah  in  1659.  Appendix  I:  Geological  Report  by 
Henry  Engelmann,  p.  313. 

MON  I 14 


210 


LAKE  BONNEVILLE. 


The  list-  of  species  wns  soiiifwlint  iiicrcMscd  liy  tlic  (■<i]lect,ions  Jifterwanl 
made  by  Howell  and  the  writer,  and  still  I'urther  additions  have  been  made 
by  the  present  Geological  Survey.  The  last  and  largc^st  collection  has  l)een 
studied  by  Call.'     The  following  list  is  liascd  chieHy  oii  his  dctcnniuations. 

List  of  MoUiisttDi   Fo^iftih. 


(.'oncIuiV^rs : 

Anixlonta  iiiif talliana,  Lea. 
SiiliM^riuiii  (lontatuni,  Hald. 
Aiiuatic  gasteropods. 

Hi'lisoina  trivolvis,  Say. 
GyrauliiH  parvus,  Say. 
Liiunopbysa  paluslris,  Miill. 

KUMiassi,  Bairil. 

boiiiievilk'iisis,  Call. 

desidiosa,  Say. 
Liinna'a  8tagnalis,Linn. 
Physa  gyrina,  Say. 


Aquatic  gaHt('r<)|»ods — Conthnifit. 
Physa  lietci<istr<i|ilia,  Say. 

lonli,  ISainl. 
Aniuicola  porata,  Maid. 

cinciniiati'iisiH,  Anth. 
Fliiiuiiiicola  fusca,  Hald 
Valvata  vircns,  Tryoii. 

sincera,  var.  iitahensiH,  Call. 
I'oiiiatiopsis  lustiica,  Say. 
Terrestrial  gastcmpoil. 

Succinoa  liueata,  W.  G.  B. 


This  list  includes  but  one  extinct  form,  AmuicoJd  honneviUensl<t.  The 
genus  Anodonta  is  represented  only  by  flaky  fragments,  but  the  abundance 
of  A.  nuttaUiana  in  the  existing  waters  of  the  Great  Basin,  and  its  occurrence 
in  Pleistocene  strata  in  other  parts  of  the  Great  Basin,  render  the  specific 
reference  highly  probable.  Sphcerimn^  Gyraulus,  Limncea,  Physa,  Valvata, 
and  Succinea  were  found  only  on  the  surface  of  the  desert,  but  their  distri- 
bution connects  them  unmistakably  with  the  ancient  lake.  The  Ostracoda 
are  represented  by  a  species  of  Ci/pris,  which  has  been  found  at  A-arions 
horizons  in  the  White  Marl  and  Yellow  Clay.  Its  occiuTence  is  sporadic, 
l)ut  in  a  few  localities  its  valves  are  so  abundant  as  to  constitute  the  entire 
mass  of  certain  thin  layei's.  Diatoms  abound  in  certain  portions  of  the 
White  Marl,  but  have  not  been  found  in  the  Yellow  Clay.  Only  a  single 
occurrence  of  vegetal  matter  has  been  noted;  at  Lemington,  close  to  the 
ancient  shore,  a  stratum  of  the  Yellow  Clay  contains  numerous  steins  and 
roots  of  a  rush,  identified  by  Dr.  George  Vasey  as  belonging  to  the  genus 
Scirpus. 

No  mammalian  remains  of  any  sort  have  been  obtained  from  the  lake 
beds  proper,  but  the  alhi\ium  of  tlu^  deltas  has  yielded  hones  at  several 


I  On  tliii  Quaternary  and   K.-cmit  MoUusca  of  tlio  Great  Hasin,  I.y  1{.  Ellsw.irtli  Call:  Bull.  W  S. 
Geol.  Survey  No.  II.  1884. 


FOSSIL  SHELLS.  211 

points.  Such  as  have  faUen  iiii(h'i'  tlie  writer's  oliservatioii  nre  so  poorly 
preserved  and  so  t'nvf^mentary  as  to  convey  no  infornuitiou  with  rci;;inl  to 
the  species  or  even  ^-I'nera  rcjirescnteil.  A  skull  suppos('(l  to  lia\c  been 
olitiiincil  from  ISonncNJllc  i;r;i\cls  at  Salt  Lake  City,  A\'iis  idcntH'HMJ  hy 
1*.  A.  ( 'hadliourne  as  helonniuf;'  to  the  Musk  ox;'  l»ut  tlic  writer  liiis  l)een 
unahle  to  satisfy  himself  as  to  the  precise  localit\',  ;uid  the  close  juxtapo- 
sition of  Tertiarv,  Pleistocene,  and  recent  strata  makes  the  reference  to  the 
Pleistocene  doubtful.  Kiny  reports  the  discoverv  in  ])()st-15onne^'ine  gravels 
of  Bisdi/  latifroHS  and  hones  of  reindeer  (?);"  and  elephantine  l)ones  and 
ivory  were  taken  from  a  post-Bonueville  marsh  at  Springville,  near  the 
eastern  shore  of  Utah  Lake. 

The  meajferness  of  this  record  is  somewhat  remarkable  \\h('u  we 
consider  that  the  lionneville  beds  constitute  the  surface  of  the  country 
throuyhout  nearly  the  extent  of  the  old  lake  l)ottoni,  and  that  tlie\'  have 
been  traversed  in  all  directions  l)y  j^ersons  interested  in  the  discoA'cry  of 
fossils  and  accustomed  to  searchin<^  for  them.  It  is  evident  that  the  condi- 
tions under  which  the  lake  beds  proper  were  de])osited  were  not  favorable 
for  the  ])reservation  of  vertebrates  or  plants  or  naiads.  We  can  not  believe 
that  such  organisms  failed  to  be  received  by  the  lake.  The  animals  which 
deposited  their  bones  in  the  deltas  must  occasionally  have  been  washed  into 
deeper  water.  Driftwood  nuist  have  found  its  way  to  the  lake  bottom,  and 
fishes  and  Anodons,  AA'liich  abound  in  all  the  rivers  and  larger  creeks  of  the 
basin,  must  have  inhabited  the  old  lake  while  it  Avas  fresh.  The  fact  that 
they  are  not  preserved  illustrates  the  fallibility  of  negative  evidence  in 
paleontology. 

JOINT   STRUCTURE. 

The  lower  course  of  the  Old  River  Bed  is  trenched  through  beds  of 
White  Marl  and  Yellow  Clay,  descending  northward  with  the  gentle  slope  of 
their  deposition.  A  few  rods  back  from  its  edge  lies  the  unfurrowed  plain, 
but  the  immediate  wall  is  scul})tured  by  short  gullies  alternating  with  crested 
ridges  of  "bad-land"  ty])e.  From  a  commanding  peak  it  was  observed  that 
the  trends  of  the  gullies  and  their  branches  exhibit  parallelism,  and  the 

I  Am.  Naturalist,  vol.  5,  p.  315.      (Cited  from  Salt  Lake  Tribune,  May  16, 1871.) 
=  Geol.  Expl.  Fortieth  Parallel,  vol.  1,  p.  494. 


212  LAKE  BONNEVILLE. 

cause  of  this  was  sought  and  found  by  Mr.  Russell.  They  are  controlled 
by  a  compound  and  extensive  system  of  joints. 

The  principal  series  trend  almost  precisely  north  and  soutli,  and  a  sidj- 
ordinate  series  east  and  west.  They  all  are  vertical  and  strai<j;-lit,  and 
(within  each  series)  closely  parallel.  They  are  readily  traced  from  top  to 
bottom  of  the  walls  of  the  lateral  ravines,  and  not  infrequently  a  wall 
exhibits  a  broad,  flat,  sheer  face,  caused  by  the  removal  of  the  clay  from 
one  side  of  a  plane  of  jointing.  Elsewhere  the  faces  of  the  bluffs  are  but- 
tressed by  square  pilasters,  or  ornamented  by  outstanding  rectangular  col- 
umns, the  forms  of  which  have  been  determined  by  the  two  systems  of  joints. 
The  main  arroyos  leading  up  from  the  river  bed  are  controlled  by  the  main 
system  of  joints,  but  at  a  short  distance  back  from  the  bluff  there  is  a  trib- 
utary drainage  at  right  angles  to  the  primary,  and  controlled  by  the  cross 
joints.  The  edge  of  the  desert  plain  is  thus  marked  out  in  a  series  of  rudely 
rectangular  blocks,  which  may  be  regarded  as  the  incipient  stages  of  the 
pilasters  of  the  bluff. 

The  lamination  of  the  clays  and  marls  in  which  the  joints  occur  is  trace- 
able across  them,  showhig  that  there  have  been  no  faults  upon  their  planes; 
and  the  absence  of  faults  is  also  attested  by  the  perfect  continuity  of  the 
even  surface  of  the  plain  at  a  little  distance  from  the  river  bed. 

Mr.  Russell's  observations  showed  that  the  joints  are  not  restricted  to 
the  spot  Avhere  they  Avere  first  detected,  but  are  discernible  generally  along 
the  margin  of  the  river  bed.  It  is  impossible  to  trace  them  u})on  the  adj;i- 
cent  plain,  but  there  can  be  little  doubt  that  they  extend  beneath  it.  The 
surface  is  converted  by  every  shower  into  a  plastic  mud,  and  in  that  condi- 
tion is  welded  into  continuity,  obliterating-  all  trace  of  structure.  For  aught 
that  is  known  to  the  contrary,  they  may  exist  in  the  lake  beds  beneath  the 
surfnce  of  the  entire  desert. 

Through  the  pages  of  the  American  Journal  of  Science,'  I  called  the 
attention  of  geologists  to  these  joints,  pointing  out  that  they  were  not  expli- 
cable on  any  existing  theory  for  the  origin  of  such  structures.  They  are  not 
faults.  Their  parallelism  shows  thev  are  not  shrinkage  cracks.  Travers- 
in"-  Pleistocene  beds  that  lie  unindurated  and  undisturbed  in  the  attitiule  of 


I  Am.  Joiir.  Sci.,  3(1  series,  vol.  23,  1882,  pp.  25-27;   vol.  24,  1882,  pp.  r)0-r>3. 


POST-BOi^NEVlLLE  JOINTS.  213 

deposition,  they  can  not  have  resulted  from  horizontal  pressure  and  com- 
pression. I  had  no  explanation  to  offer,  but  my  inquiry  led  to  the  ]jidjlica- 
tion  of  one  so  accordant  with  the  phenomena  that  it  at  once  takes  rank  as 
the  working  hypothesis  for  the  origin  of  all  ])arallel  jointing  except  slaty 
cleavage.  It  was  offered  independently  by  Crosby^  and  Walling,^  and  the 
force  appealed  to  is  the  earthquake.  During  the  passage  of  an  earthquake 
wave  the  earth  material  traversed  is  subjected  to  momentary  strains  of  com- 
pression and  tension  in  the  direction  of  wave  transmission,  and  to  shearing 
strains,  instantly  reversed,  in  a  direction  normal  to  that  of  wave  transmission. 
At  each  instant  the  similar  elements  of  the  wave  constitute  a  surface  approx- 
imately spherical  or  ellipsoidal,  with  the  locus  of  wave  origin  at  its  center, 
and  at  any  locality  remote  from  the  locus  of  origin  such  surface  is  sensibly 
a  vertical  plane.  Assuming  the  competence  of  the  strains  to  create  a  rock 
structure,  their  directions  and  arrangement  show  that  the  structure  should 
ordinarily  exhibit  vertical  parallel  planes. 

Under  this  theory  the  two  series  of  joints  at  the  Old  River  Bed  indicate 
two  earthquake  directions  and  at  least  two  efficient  earthquakes.  As  the 
joints  extend  as  simple  regular  planes  to  the  very  margin  of  the  old  channel, 
and  as  they  determine  the  directions  of  arroyos  initiated  immediately  after 
the  excavation  of  tlie  channel,  it  is  probable  that  they  were  formed  while 
the  lake  sediments  were  yet  continuous  and  unchanneled.  We  are  thus  told 
of  eartliquakes  occurring  just  before  the  retreat  of  the  lake  laid  bai'e  the 
White  Marl. 

That  the  Bonneville  Basin  was  subject  in  Bonneville  and  post-Bonne- 
ville  time  to  numerous  earthquakes  of  the  type  of  the  great  Californiau 
earthqiiake  of  1872,  is  abundantly  shown  by  the  phenomena  of  fault  scarps 
described  in  Chapter  VIII;  and  the  distribution  of  the  fault  scarps,  so  far 
a.s  it  is  known,  accords  well  with  the  strike  of  the  principal  system  of  joints. 

'  On  the  classification  and  origin  of  joint-structure.  By  W.  O.  Crosby.  Proc.  Boston  Soc.  Nat. 
Hist.  vol.  22,  1882,  pp.  72-85. 

*0n  the  origin  of  joint  cracks.  By  H.  F.  Walling.  Am.  Ass.  Adv.  Sci.  vol.  31,  Montreal  meeting, 
1882,  p.  417. 


CHAPTER     VI. 
THE  HISTORY  OF  THE  BONNEVILLE  BASIN. 

THE  PRE-BONNEVIIiliE  HISTORY. 

The  latest  Tertiary  series  outcr()})ping  within  the  Bonneville  basin  has 
a  distribution  quite  independent  of  the  basin.  Not  only  do  its  strata  occiir 
in  the  mountains  above  the  shore-lines,  but  they  override  some  of  the  passes 
on  the  rim  of  the  hydi'Ographic  basin  .and  extend  continuously  to  the  di'ain- 
age  of  the  Snake  River,  and  possibly  to  that  of  the  Humboldt.  On  the 
other  hand,  the  Neocene  strata  have  not  been  found  in  the  southern  third 
of  the  Bonneville  area.  It  is  probable,  therefore,  that  the  hydrography  of 
the  Neocene  and  that  of  the  Pleistocene  corresponded  to  configurations  of 
the  surface  essentially  different.  The  Bonneville  Basin  was  not  m  existence 
during  the  period  when  the  Neocene  sediments  were  deposited;  its  history 
began  at  some  later  date,  after  the  deformation  of  the  earth's  crust  which 
elevated  the  Neocene  strata  uj)on  the  mountain  flanks  had  wrought  im- 
portant changes  in  the  face  of  the  land. 

The  area  formerly  covered  by  the  main  body  of  Lake  Bonneville  is 
now  a  plain,  conspicuous  for  its  flatness.  Great  Salt  Lake,  i-esting  on  its 
surface,  has  a  mean  depth  of  but  fifteen  feet;  and  a  rise  of  a  few  feet  only, 
as  pointed  out  by  Stansbury,  would  extend  it  westward  over  the  greater 
portion  of  what  is  known  as  the  Great  Salt  Lake  Desert.  The  (K^currcnce 
of  such  a  plain  at  an  elevation  of  4000  feet  above  the  sea,  and  in  the  midst 
of  a  region  characterized  by  mountains,  admits  of  but  one  explanation, 
namely,  lacustrine  sedimentation.  Th(^  narrow  ridges  tliat  in  places  inter- 
rupt tlie  continuity  of  tlie  plain  sliow  tliat  tlie  district  did  not  escape  the 
general  process  of  erogenic  corrugation  to  wliich  tlie  (Jreat  Basin  was  sub- 

214 


THE  FLATNESS  OF  THE  DESERT.  215 

jected,  and  there  seems  no  reason  to  believe  that  the  disphiceraents  were 
here  less  profound  than  elsewhere.  Certainly  the  degradation  of  the  sum- 
mits has  been  sufficient  to  lay  bare  in  places  Cambrian  and  even  Archean 
i-ocks.  Moreover,  the  habit  of  these  ridges  is  peculiar,  and  itself  indicates 
burial.  The  normal  mountain  ridge  of  the  Great  Basin  is  acutely  serrate 
along  its  crest,  and  disjjlays  naked  rock,  deeply  carved  into  gorges  and 
amphitheaters  down  to  a  certain  line.  Below  that  line  the  slopes  are 
gentler,  the  contours  are  smooth,  and  the  material  is  alluvial,  the  waste  from 
the  sculpture  above.  The  gorges  above  and  the  alluvial  cones  below 
are  to  a  certain  extent  correlative,  but  the  mass  of  the  latter  is  derived  from 
the  general  degradation  of  the  mountain  summit  as  well  as  the  excavation 
of  the  canyons.  The  mountains  and  buttes  of  the  Salt  Lake  Desert  conform 
to  the  Great  Basin  type  in  the  characters  of  their  summits,  but  are  almost 
devoid  of  alluvial  cones.  They  spring  from  the  plain  so  abruptly  that  the 
frontiersman  as  well  as  the  geologist  has  I'ecognized  them  as  incomplete,  or 
rather,  as  partially  submerged,  and  has  named  them  accordingly.  One  of 
them  is  known  as  Newfoundland,  another  as  Silver  Islet,  a  third,  which 
towers  3,000  feet  above  its  base,  as  Granite  Rock;  and  geuerically  they  are 
spoken  of  as  "lost  mountains".  How  deep  beneath  the  lacustrine  ))lain 
their  bases  lie,  it  is  impossible  to  say,  but  2,000  feet  is  certainly  a  moderate 
estimate. 

Not  all  of  this  lacustrine  filling  can  be  ascribed  to  the  Pleistocene,  and 
not  all  of  it  belongs  to  tlie  history  of  the  Bonneville  Basin  as  such.  The 
Neocene  lake,  and  possildy  earlier  lakes,  have  contributed  a  sliai-e,  and  this 
before  the  hydrographic  basin  of  Lake  Bonneville  was  established.  Since 
the  establishment  of  the  basin,  sedimentation  has  been  practically  continuous 
in  its  lowest  depression.  If  we  conceive  the  local  climate  to  have  under- 
gone a  rliythmic  series  of  clianges,  the  area  of  lacustrine  sedimentation  lias 
alternately  expanded  and  coiitracted,  and  lias  always  iiududed  tlie  lowest 
depression;  and  even  witli  a  climate  so  dry  as  to  maintain  no  })ereimial 
lake,  the  temporary  floods  occasioned  by  exceptional  storms  must  still  have 
continued  the  process  of  accumulation.  The  situation  of  the  lowest  dei)res- 
sion  may  have  varied  from  time  to  time,  as  local  displacements  of  the  earth's 
crust  modified  the  configuration,  but  wherever  it  was,  it  was  the  scene  of 


216  LAKE  BONNEVILLE. 

sedimentation,  and  the  constant  tendency  of  tlie  lacustrine  process  was  to 
fill  the  minor  depressions  and  reduce  the  floor  of  the  basin  to  a  level  surface. 
The  evenness  of  the  desert  plain  testifies  to  its  lacustrine  origin. 

Tlic  process  of  filling'  might  have  been  modified,  but  would  not  have 
been  interru})ted,  by  an  overflow  of  the  water  of  the  liasin  such  as  occui-red 
in  the  Bonneville  epoch.  As  long  as  the  basin  was  not  drained  to  its  lowest 
depths,  those  depths  would  continue  to  receive  detrital  deposits,  and  the  out- 
flowing water  would  carry  with  it  only  the  soluble  products  of  the  degra- 
dation of  the  surface  of  the  basin.  Whether  such  an  overflow  ever  took 
place  is  not  apparent;  but  if  it  did,  we  may  l)e  sure  that  its  date  was  remote 
as  compared  to  the  Bonneville  epoch.  The  lower  passes  of  tlu^  l>asin's  rim 
show  no  traces  of  an  ancient  channel,  and  the  time  necessary  for  the  efface- 
ment  of  such  traces  must  be  reckoned  as  long  in  comparison  to  the  antiquity 
of  the  Bonneville  shore-lines.  Upon  most  of  the  passes  the  process  would 
include  the  growth  of  great  alluvial  fans;  and  at  Red  Rock  Pass,  where  the 
Bonneville  discharge  took  place,  the  record  of  an  earlier  discharge  could 
ha^•e  been  obliterated  only  by  the  restoration  of  the  Marsh  Creek  alluvial 
fan,  and  its  extension  so  as  to  fill  the  channel  of  outflow  for  many  miles  in 
Marsh  Creek  Valley.  When  we  consider  that  no  stream  so  small  as  Marsh 
Creek  is  known  to  have  built  a  delta  on  either  the  Bonneville  or  the  Provo 
shore,  it  becomes  evident  that  such  obliteration  implies  a  period  vastly  longer 
tlian  that  consumed  by  the  Bonneville  oscillations.  As  far  back,  then,  as  we 
may  hope  to  obtain  a  consecutive  view  of  the  history  of  the  basin,  its  waters 
had  no  period  <  )f  discharge  save  that  of  the  Bonneville  epoch.  It  was  a  closed 
basin,  and  the  area  of  its  lake  surface  was  determined  by  the  relation  be- 
tween its  water  supjjly  and  the  rate  of  evaporation.  Tlie  lake  area  was, 
therefore,  a  function  of  climate,  provided  the  extent  of  the  hydrogra])hic 
basin  remained  unchanged.  To  avoid  any  possible  misinterpretation  of 
the  climatic  historj'  it  is  important  that  the  possibility  of  variation  in  the 
hydrographic  basin  receive  full  attention. 

The  general  altitude  of  the  country  to  the  east  of  the  basin  is  several 
thousand  feet  greater  than  that  to  the  west,  north  and  south,  and  at  least  95 
per  cent,  of  all  the  water  flowing  into  the  modern  lakes  is  furnished  by  the 
eastern  highlands.     These  include  the  Wasatch  Mountains,  a  portion  of  the 


ANTIQUITY  OF  THE  BONNEVILLE  BASIN.  217 

High  Plateaus  lying  to  the  south,  a  portion  of  the  Uinta  Mountains  lying 
to  the  east,  and  a  mountainous  tract  lying  to  tlie  northeast  in  western  Wyom- 
ing and  southeastern  Idaho.  Tlie  low  country  to  the  west  of  the  basin  is 
di\idcd  l)y  mountain  ranges  into  numerous  independent  drainage  districts, 
and  these  have  not  been  so  thoroughly  studied  as  to  determine  what  would 
be  their  hydrographic  combinations  in  the  event  of  a  more  generous  rainfall. 
We  know,  however,  that  they  contribute  nothing  now  to  the  water  sup[)ly 
of  the  basin,  and  that  in  Bonneville  times  their  tribute  was  small;  and  we 
are  thus  assured  that  in  pre-Bonneville  times  the  supply  from  that  side  was 
not  less  than  at  present.  It  will  be  shown  hereafter  that  the  possibility  of  a 
greater  contrilnition  from  this  region  does  not  materially  affect  the  conclu- 
sions in  regard  to  climate.  The  same  remarks  apply  to  the  region  south  of 
the  Escalante  Desert.  North  of  the  Bonneville  Basin  the  conligurntion  of 
the  country  about  the  water  parting  does  not  suggest  any  possible  change 
in  its  position  during  the  period  under  consideration. 

The  water  supply  from  the  east  reaches  the  lower  portions  of  the  basin 
by  four  rivers:  the  Sevier,  the  Jordan,  the  Weber,  and  the  Bear;  and  its 
drainage  system  is  correspondingly  divided  into  four  j)arts.  The  Sevier  River 
rises  in  what  Button  has  called  the  High  Plateaus,  and  is  separated  by  high 
divides  from  the  drainage  tif  the  Fremont,  tlu-  Escalante,  the  Paria,  and  the 
Virgen,  branches  of  the  Colorado  of  the  West.  The  Paunsagunt  and  tlie 
^larkagunt  })lateaus,  which  constitute  the  most  southerly  elements  of  its 
drainage,  are  slowly  diminishing  in  area  through  the  sapping  and  recession 
of  cliffs,  and  the  hydrograjjhic  basins  of  the  Paria  and  Virgen  are  thus  grow- 
ing at  the  expense  of  the  Sevier.  A  less  considerable  change  of  the  opposite 
tendency  is  in  ])rogress  at  the  head  of  Moraine  Valley,  where  a  plateau 
draining  to  the  Fremont  River  is  encroached  on  by  the  recession  of  cliffs 
draining  to  the  Sevier.  The  effect  of  these  slow  changes  upon  the  water 
sujiply  of  the  Bonneville  Basin  can  not  have  been  important,  and  there  is  no 
evidence  that  any  considerable  tracts  have  bodily  transferred  their  allegiance. 

The  Jordan  includes  among  its  branches  the  American  Fork,  the  Provo, 
the  Spanish  Fork,  and  Salt  Creek. 

It  is  quite  possible  that  Salt  Creek  has  changed  its  course  within  the 
basin,  and  that  it  was  at  one  time  connected  with  the  Sevier  and  not  per- 


218  LAKE  BONNEVILLE. 

manentlv  with  tlie  Jordiin,  ])ut  ^uch  ;i  cliaiige  is  of  no  nioiiR'nt  in  this  con- 
nection. American  Fork  and  Sjnini.sli  Fork  head  a<^ainst  liigh  divides,  who.se 
po.sition  must  liave  l)een  permanent  for  a  hmg  period.  Tlie  same  remark 
ai)pHes  to  thc^  I'rovo  River,  but  there  is  one  point  in  its  course  where  its 
chainiel  is  not  contained  by  soHd  rock  and  its  water  could  easily  be  diverted. 
Kamas  Prairie  is  a  .small  valley  lying-  athwart  the  western  end  of  the  Finta 
Rauffe.  The  Provo  River  crosses  the  southern  end  of  the  vallev,  enterinjj 
by  one  canyon  and  leaving  by  another;  and  the  Weber  Riv6r  in  like  manner 
crosses  its  northern  end.  The  configuration  of  the  plain  .shows  that  the 
streams  have  not  always  been  separate;  at  one  time  the  Provo  turned 
northward  in  the  valley  and  was  tributary  to  the  Weber.  Here,  however, 
as  in  the  case  of  Halt  Creek,  the  modifications  of  the  drainage  do  not  affect 
tlio  water  supply  of  the  Bonneville  Basin. 

The  drainage  district  of  the  Weber  is  so  nearly  embraced  at  the  east 
by  the  basins  of  the  Bear  and  the  Jordan,  that  the  only  portion  of  its 
boundary  coincident  with  that  of  the  Bonneville  drainage  district  is  a  high 
crest  in  the  Uinta  ^fountains  two  or  three  miles  in  length.  Variations  in  its 
course  and  drainage  area  are  therefore  unimportant  to  the  present  discus- 
sion; and  the  same  remai-k  applies  to  the  American  Fork  and  to  the  series 
of  creeks  issuing  from  the  west  face  of  the  Wasatch  ]\Ioinitains. 

The  Bear  is  the  most  important  of  all  the  rivers,  and  has  many  tribu- 
taries. Its  main  brandi  lieads  in  the  Uinta  Mountains,  and,  .so  far  as  may 
l)e  judged  from  tlu^  maj)s  of  th(^  Fortieth  Parallel  Survey,  is  surrounded  by 
high  divides,  affonling  little  opportunity  for  tran.snmtations  of  drainage. 
Smith  F(jrk  and  Tliomas  Fork,  which  join  it  in  midcourse,  occupy  ])asins 
contiguous  to  those  of  Salt  River  and  John  Day  River,  tributaries  to  the 
Snake.  These  basins  have  been  mapped  by  the  Geological  Survey  of  the 
Territories,  and  the  testimony  of  the  contours  is  sustained  by  that  of  Mr. 
Henry  Gaimett,  who  perfonned  the  topographic  work  and  who  states  that 
the  conformation  indicates  permanence  of  drahiage.  In  its  lower  course 
(in  ( "aclie  Valley)  the  river  receives  a  large  innnl)cr  of  tributaries,  l)ut  mtne 
of  their  drainage  districts  extend  to  the  rim  of  the  Bonneville  Basin.  The 
sources  of  the  river  appear  thus  to  offer  no  suggestion  of  an  ancient  variation 
of  the  drainage  area;  but  there  is  one  point  in  its  course  of  which  the  same 


POSSIBLE  CHANGES  OF  CATCHMENT  AREA.  219 

can  not  be  said.  After  receiving  the  waters  of  Smith  Fork  and  Thomas 
Fork,  and  before  entering  Cache  Valley,  the  river  swings  far  to  the  north, 
apiiroaching  very  near  to  the  rim  of  the  Bonneville  Basin.  At  Soda  Springs 
it  is  separated  from  tlie  sonth  fork  of  the  lilackfoot  River,  a  l)ninc]i  of  the 
Snake,  hy  a  divide  rising  fonr  or  five  hnndred  feet  above  the  Bear,  bnt  only 
slightly  elevated  above  the  Blackfoot.  A  few  miles  lower  down  it  crosses 
the  sonthern  end  of  a  broad  open  valley  (IJ5asalt  Valley),  the  northern  end 
of  wliieli  is  traversed  by  the  Portnenf  River,  likewise  a  branch  of  the  Snake. 
The  Portnenf  is  here  the  lower  stream,  and  the  water  parting  between  the 
two  rivers  runs  close  to  the  course  of  tlie  Bear.  It  is  probably  not  more 
than  one  or  two  liundred  feet  above  the  bed  of  the  Bear.  In  the  Soda 
Springs  pass,  the  sumniit  is  ftirmcd  liy  ])asalt,  l}ing  in  horizontal  sheets  and 
associated  with  cinder  cones  and  other  evidence  of  recent  eruption.  The 
princii)al  masses  are  jjrobably  more  ancient  tliiiu  tlie  Bonneville  epoch,  l)ut 
they  have  not  suffered  those  dislocations  which  are  apt  to  be  observed  in 
this  region  in  the  case  of  rocks  dating  far  back  in  the  Tertiary.  It  is  believed 
by  Mr.  Gannett  and  by  ^\r.  Gilbert  Thomj)son  that  their  eruption  has 
affected  the  drainage  system  of  the  region  in  ways  that  are  yet  discernible, 
and  it  is  possible  that  they  have  wrought  a  separation  of  the  Blackfoot  and 
the  Bear.  If  the  two  streams  were  anciently  united,  it  is  most  probable 
that  the  Blackfoot  was  tril)utary  to  the  Bear;   but  the  reverse  is  possible. 

At  the  Basalt  Valley  i)ass  the  phenomena  are  essentially  the  same. 
The  broad  valley  extending  from  the  chaimcl  oi'  tlic  Bear  to  that  of  the 
Portnenf  is  covered  throughout  by  basaltic  la\a,  and  portions  of  this  lava 
are  so  recent  that  associated  scoriaceous  craters  are  still  preserved.  Befoi-e 
the  epoch  of  eruption,  the  Bear  and  Portnenf  Rivers  may  have  been  joined, 
and  their  united  water  may  have  flowed  either  to  the  Snake  River  or  to  the 
Bonneville  Basin. 

If  the  south  fork  of  the  Blackfoot  were  uo\\  to  be  diverted  to  the  valley 
of  the  Bear  River,  as,  according  to  Mr.  Thompson,  it  readily  might  be,  the 
Salt  Lake  drainage  basin  would  be  increased  by  350  square  miles  of  upland. 
If  the  canyon  of  the  Portnenf  below  Basalt  Valley  were  dammed,  so  as  to 
turn  its  water  toward  Bear  River,  500  square  miles  would  be  added  to  the 
basin.     If  another  eriq)tion  were  to  dam  Bear  River  aljove  Gentile  Valley 


220  LAKE  BONNEVILLE. 

and  divert  it  to  tlie  v;vlloy  of  the  Portnenf,  the  Bonneville  Basin  would  lose 
about  one-fourth  of  its  water  supply.  All  speculation  in  rejj^ard  to  the  pre- 
Bonneville  climate  of  the  l)asin  is  therefore  subject  to  the  possi])ility  that 
the  catchment  basin  niay  on  the  one  hand  have  been  sliyhtly  greater  or 
may  on  the  other  have  been  very  materially  less. 

ALLUVIAL  CONES  AND  ARIDITY. 

The  principnl  evidence  bearing  on  the  pre-Bonneville  history  of  the 
l)asin  is  embodied  in  the  alluvial  cones.  These  extend  nearly  to  the  l^ottom 
of  the  basin,  and  since  they  could  not  have  been  shaped  in  the  pi*esence  of 
a  large  lake,  it  is  concluded  that  the  epoch  of  their  formation  was  an  epocii 
of  low  water.  The  dependent  conclusion  that  the  pre-Bonneville  ei)ocli 
was  characterized  by  aridity  is  of  such  importance  that  a  little  space  Avill 
be  de^•oted  to  the  amplification  of  these  propositions. 

'V\n'  drainage  of  a  mountain  mass,  starting  in  innumerable  rills,  gathers 
into  a  smaller  number  of  rivulets,  and  is  finally  aggregated  into  a  verv  few 
main  streams  before  issuing  from  its  self-carved  gorges.  The  outward  borne 
detritus  is  therefore  delivered  to  the  adjacent  valley  at  a  limited  number  of 
points  separated  by  interspaces.  Each  point  of  issue  becomes  the  apex  of 
a  sloping  mass  of  alluvium  whose  surface  inclines  equably  in  all  directions. 

A  series  of  such  alluvial  cones  is  usually  to  be  found  along  the  base  of 
each  mountain  range,  constituting  a  foot  slope,  the  contours  of  which  are 
scalloped.  The  topographic  configuration  which  thus  arises  is  peculiar  and 
not  liable  to  be  confounded  with  any  other. 

It  has  already  been  stated  that  the  alluvial  bases  of  the  insular  mount- 
ains of  the  Bonneville  Basin  are  buried  by  lacustrine  sediments.  Those  of 
the  peripheral  mountains  are  not  so  buried,  or  at  least  are  not  so  dee})ly 
buried,  and  the  forms  of  their  cones  can  at  many  localities  be  traced  down- 
ward to  the  lower  levels  of  the  basin.  The  shore-lines  are  locall\-  mai-kcd 
upon  the  cones,  cliffs  and  terraces  being  excavated  from  them  and  ciuhaiik- 
ments  built  against  them;  but  where  the  cones  are  large,  these  modifica- 
tions are  relativelv  small  ;ind  do  not  materialh-  impair  the  general  con- 
figuration. Good  illustrations  are  to  be  found  in  i'reuss  Valley,  in  White 
Valley,  at  the  eastern  base  o(  the  Deep  Creek  and  Gosiute  Mountains,  and 


DRY  CLIMATE  BEFORE  LAKE  EPOCH.  221 

on  1  )()th  sides  of  Pilot  Creek.  There  are  fine  examples  also  in  Tooele  Valley, 
Skull  Valley  and  Blue  Creek  Valley. 

The  phenomena  of  the  Bonneville  shores  illustrate  the  fact  that  the 
buildinji-  of  alluvial  cones  is  arrested  by  lacustrine  conditions.  p]ither  the 
stream  constructs  a  delta,  which  is  an  alluvial  fan  above  the  water  but  ter- 
minates in  a  submerged  cliff  at  the  water  edye;  or  else,  the  stream  being 
small,  its  load  of  detritus  is  absorbed  by  the  shore  drift.  In  the  latter  case, 
some  point  of  the  alluvial  cone  is  usually  trenched  on  by  the  waves,  a  cliff 
and  terrace  being  jjroduced;  and  whenever  the  stream,  which  had  ])reviously 
shifted  its  course  over  the  whole  surfiice  of  the  cone,  assumes  a  direction 
leading  to  this  cliff,  it  is  enabled  })y  the  lowering  of  its  l^ase  level  to  exca- 
vate a  more  permanent  channel,  from  which  it  does  not  quickly  escape. 

It  is  therefore  leg-itimate  to  reg'ard  the  formation  of  alluvial  cones  as  a 
stiictly  subaerial  process,  and  to  conclude  that  the  Bonne\ille  Basin  con- 
tained no  large  lake  during  the  pre-Bonneville  period  when  its  alluvial  cones 
were  formed. 

I  do  not  overlook  the  possibility  that  traces  of  an  epoch  Avlien  the 
waves  held  sway  may  have  been  obliterated  by  the  alluviation  of  a  later 
epoch,  but  in  my  judgment  such  considerations  do  not  impair  the  general 
conclusion.  Within  the  masses  of  the  alluvial  cones  there  niay  be  liuried 
shore  cliffs,  shore  embankments,  and  lacustrine  sediments,  but  the  time 
necessary  for  the  oliliteration  in  this  nuiuner  of  a  record  similar  to  that  of 
the  Bonneville  lake  is  as  long  as  tlie  time  necessary  for  the  obliteration  of 
a  channel  of  outflow,  and  is  certainly  very  long  as  compared  to  the  dura- 
tion of  the  Bonneville  epoch. 

Let  us  call  this  relatively  long  epoch  antecedent  to  the  Bonneville,  the 
pre-Bonneville  epoch.  We  have  found  reason  to  believe,  first,  that  the 
basin  had  then  no  outlet,  and,  second,  that  the  basin  did  not  then  contain 
a  large  lake.  The  size  of  an  inclosed  lake  being  determined  l)y  the  ratio  of 
water  supply  to  rate  of  evaporation,  it  follows  that  that  ratio  was  small.  If 
the  hydrographic  area  remained  unchanged,  the  water  supply  as  well  as  tlie 
rate  of  evaporation  depended  upon  climate,  and  tlie  climate  must  have  been 
arid.  If  the  main  branch  of  Bear  River  was  then  tributary  to  the  Portneuf 
Basin  instead  of  the  Bonneville,  a  greater  climatic  change  would  have  been 


222  LAKE  BONNEVILLE. 

necessary  to  flood  the  basin,  and  the  hidicated  aridity  of  climate  is  corre- 
spondingly less. 

THE  POST-BONNEVILLB  HISTORY. 

l^lie  closiu'i'  event  of  the  Hoiiiicn  illc  liist(ii'\'  \v;is  the  (Icsiccatioii  uf  the 
basin.  \  ft'W  stii<i'{'s  in  tlm  retiiX'inciit  ut  the  water  are  rcc()r(ic(l  \)\  tiie 
Stansl)ury  and  lower  shore-lines,  bnt  xi-vy  little  information  is  dbtainable  in 
regard  to  the  oscillations  which  may  have  interru})ted  the  retirement,  for 
the  reason  that  no  natui-al  sections  of  the  deposits  exist.  If  oscillations  took 
place  they  nuist  have  wrought  the  superposition  of  littoral  and  subacpieous 
dejjosits,  but  the  record  of  such  superposition  can  be  read  only  when  new 
general  conditions  shall  have  exposed  thi'  lower  reaches  of  the  l)asiu  to 
stream  erosion. 

SUBDIVISION   OF  THE  BASIN. 

One  effect  of  the  desiccation  was  the  subdivision  of  the  Bonneville 
Basin.  Not  merely  was  the  Sevier  Desert  set  off  from  the  basin  of  (Jreat 
Salt  Lake,  but  a  numbcn-  of  smaller  basins  became  equally  distinct,  'i'he  list 
of  independent  drainage  districts  includes  at  the  present  time  the  Escalante 
Desert,  the  Sevier  Desert,  Preuss  Valley,  White  Valley,  Snake  Valley  from 
the  Salt  Marsh  southward.  Rush  Valley,  Cedar  Valley,  the  u))per  portion  of 
Pocatello  Valley,  the  Pilot  Peak  basin,  and  the  basin  of  Great  Salt  Lake. 
It  is  possible  that  Snake  Valley  contains  two  drainage  basins  instead  of  one, 
and  there  is  some  reason  also  to  suppose  that  the  broad  expanse  of  the  Great 
Salt  Lake  Desert  west  of  the  Cedar  Range  is  a  distinct  basin.  The  mutual 
relations  and  the  relative  size  of  these  basins  are  shown  in  PI.  XII. 

Three  of  them  contain,  (.)r  are  known  to  have  contained,  perennial  lakes; 
the  others  have  playas  in  their  lowest  depressions,  where  water  gathers 
after  every  storm  but  does  not  persist  throughout  the  year.  On  the  Great 
Salt  Lake  Desert  the  earth  constituting  the  playa  is  exceedingly  fine  and 
affords  in  dry  weather  a  hard  sui-fiice  of  a  pale  yellow  color.  In  ))laces,  and 
especially  toward  the  margins  of  the  area,  it  is  less  compact,  and  is  super- 
ficially covered  witli  saline  efflorescence.  A  little  i-ain  renders  the  surface 
soft  and  adhesive,  and  the  depth  to  which  tliis  change  may  extend  seems 
limited  only  by  the  supply  of  moisture.  The  same  description  ajiplies  to 
Preuss  Valley,  White  Valley,  and  the  Escalante  Desert,  except  that  the 


DUNES  OF  GYPSUM.  223 

playas  of  tlio  Inst  two  are  less  compart.  The  Pilot  Peak  l);isiii  lies  south- 
east of  that  mountain,  and  is  separated  trom  tlie  Great  Salt  Lake  Desert  by 
the  rang-e  kn()\\'n  as  tlie  Desert  Hills.  The  surface  of  its  playa  was  found 
by  8t;uisbury  to  be  covered  by  one  or  two  inches  of  salt.  In  the  south- 
eastern ani^'le  of  the  Sevier  Desert  there  is  a  tract  jiartially  partiti(tned  fi-om 
the  pft'iieral  plain  by  a  series  of  coulees  of  ))asaltic  lava,  extravasated  during- 
the  Bonneville  epoch.  This  contains  several  playas,  marking  localities  where 
the  drainage  is  checked  but  not  completely  imprisoned.  The  highest  and 
most  southerly  of  these  differs  from  all  the  others  in  that  its  material  is  gyp- 
sum. It  is  probable  that  the  deposit  is  independent  of  any  special  chemical 
reaction,  and  is  due  simply  to  the  discharge  by  evaporation  of  a  mineral 
dissolved  from  the  rocks.  The  streams  whose  waters  occasionally  flood  the 
playa  rise  among  strata  of  Jurassic  and  Triassic  age,  and  such  strata  in  a 
neighboring  mountain  range  are  kno^vn  to  be  highly  gypsiferous.  The 
heads  of  the  streams  were  not  examined.  It  was  ascertained  by  digging  in 
the  playa  that  a  portion  of  the  deposit  is  amorphous  and  another  portion 
crystalline.  One  phase  of  the  precipitation  results  in  the  formation  of  small 
free  crystals,  which  the  wind  sweeps  from  the  surface  of  the  playa  and 
gathers  in  dunes.  The  dunes  do  not  travel  to  a  great  distance,  but  are 
an-ested  by  a  low  rhyolitic  butte  near  by,  to  which  they  have  given  the 
name  of  White  Mountain.  Perhaps  no  gypsum  deposit  in  the  world  is  so 
easily  exploited  as  this;  it  needs  merely  to  be  shoveled  into  wagons  and 
hauled  away.  Mr.  Russell  estimates  that  the  dunes  contain  about  450,000 
tons,  and  a  much  larger  amount  can  be  obtained  from  the  playa  The 
depth  of  the  playa  deposit  was  not  ascertained,  but  its  area  is  indicated  on 
PI.  XXXV. 

SNAKE  VALLEY  SALT  MARSH. 

The  lowest  depression  in  the  Snake  Valley  Basin  contains  what  is 
locall}'  known  as  a  salt  marsh;  but  the  term  as  here  used  denotes  something 
very  different  from  the  salt  marsh  of  the  seashore.  There  is  no  vegetation, 
but  simply  a  shallow  lake,  which  nearl)-  or  quite  disappears  in  summer.  In 
winter  it  has  a  depth  of  about  two  feet,  being  then  limpid  and  resting  on  a 
bed  of  soft  mud.  Near  the  lake  are  perennial  fresh  springs  which  replenish 
the  water  lost  by  evaporation.     In  winter,  when  evaporation  is  slow,  the 


224  LAKE  BONNEVILLE. 

volume  of  the  lake  increases,  and  salts  ])reviously  precipitated  are  redis- 
sdlvcd.  in  siiiiuHer  a  more  rapid  evaporation  diminishes  the  volume,  pre- 
(■ipitatin<i'  sodium  chloride  and  sodium  sulphate  and  rcduciiiii'  the  brine  to  a 
mother  litpior.  The  precipitate  has  a  depth  of  ahout  \  h  im-lies,  and  a  por- 
tion of  it  is  each  yaw  removed,  to  he  employed  as  ii  reji^'eiit  in  tlie  reihic- 
tion  of  silver  ore.  1'liis  i-emoval  has  not  been  found  to  aft'ect  juateriallv  tlie 
strennth  of  the  brine,  which  is  in  some  Avay  resu])plied  with  salt.'  It  is 
believed  by  Mr.  W.  (J.  Barry,  one  of  the  owners  of  the  marsh,  that  the 
suppl}'  is  brought  by  percolating  water  from  the  saliferous  mud  beneath  the 
lake,  and  this  tlieory  of  its  origin  tinds  support  in  the  phenomena  of  a  series 
f  salt  marshes  in  Nevada  examined  by  Mr.  Russell. 


o 


a 


SEVIER  LAKE. 

The  lowest  depression  of  the  Sevier  Desert  has  probably  been  occu- 
pied l)y  a  lake  from  the  date  of  the  earliest  exploration  nearly  to  the  present 
time,  but  i)recise  information  in  regard  to  it  dates  from  1872.  Escalante  in 
177n  crossed  the  Sevier  river  sixty  or  seventy  miles  from  the  lake,  and 
leai-ned  by  report  of  its  existence.  Fremont  did  the  same  in  liS4r).  In 
1853  Gunnison  was  killed  by  Indians  within  a  few  miles  of  the  lake  while 
on  his  way  to  explore  it.^  lieckwith  and  Simpson,  who  conducted  explo- 
rations in  contiguous  portions  of  the  Great  liasin  in  IS'),'!  and  IS.")!),  were 
aware  of  its  existence,  but  saw  it  onh  from  a  distance.^  In  18()9  Wheeler, 
jiproachingfrom  the  west,  visited  the  south  end  of  the  lake  and  determined 
its  true  position,  lie  was  unaware  of  its  identity,  however,  and,  following 
an  error  prevalent  at  that  time,  called  it  Preuss  Lake.*     It  was  reserved  foi 

'  The  stateiiioiits  regarding  this  iiiarNli  arc  cliieHy  based  on  observations  made  in  tin'  winter  of 
187y-'80. 

-Report  by  Lient.  10.  O.  Heeknitb,  n|>on  the  route  near  Uie  :?Stli  and  li'.Uli  parallels,  explored  by 
Capt.  J.  W.  Gnnnison  :  I'acilie  lvailroa<l  Explorations,  vol.  2,  pp.  72-74. 

■■Capt.  J.  H.  Simpson,  Exidorations  aiToss  the  Great  Ba.sin.  etc.,  p.  I'i't;  Licnt.  E.  G.  Reckwitb, 
Ibid.,  pp.  72,  76. 

■•See  pages  3  and  4  of  the  Preliminary  Report  of  the  General  Features  of  the  Military  Reeon- 
naisance  throngh  Southern  Nevada  [18(19]  under  Lient.  George  M.  Wheeler.  8".  [No  imprint  nor 
date,  bnt  probably  San  Francisco,  1870.]  This  report  was  reprinted  in  (jnarto  form  with  some  changes 
in  187.').  The  map  prepared  to  accompany  it  marks  "  Prenss  Lake '"  in  the  geograjjhic  position  of  Seviir 
Lake.  The  edition  of  the  U.  S.  Engineer  map  of  the  Western  Territorit^s  <latoil  18li8  gives  Sevier  and 
Preuss  as  separate  lakes,  and  most  privately  piiblisUed  ma |)s  follow  it,  lint  a  map  cd' Coltoli's  dated 
1864  gives  Sevier  Lake  only,  ruuniug  into  it  the  river  with  which  imagination  had  furuished  Preuss 
Lake. 


EXl'LOiiATlON  OF  SEVIER  LAKE.  225 

Lieut.  R.  L.  Hoxie,  linving  charge  in  1872  of  one  of  tlie  field  parties  of  tlie 
Wheeler  Survey,  to  demonstrate  the  full  hydrography  of  the  lake,  determin- 
ing its  form  and  extent  and  its  relation  to  the  tributary  stream.  The  map 
prepar<'<l  l)y  his  topogra])]ier,  Mr.  Louis  Nell,  is  copied  in  all  modern  com- 
])ilatious.  The  writer  had  the  jjleasure  to  accompany  Lieut.  Hoxie,  and 
has  since  revisited  the  locality.  Li  1872  the  lake  was  about  28  miles  in 
length  and  had  a  water  sui"f;ice  of  188  square  miles.  It  has  since  been 
ascertained  that  its  maxiiiiuin  (lei)tli  was  about  15  feet,  the  northern  portion 
being  deeper  than  the  southern.  Its  <»nly  affluent  was  tlie  Sevier  River, 
which  entered  at  the  north.  Its  l)rine  contained  <S.(!4  per  cent  of  saline 
matter,  consisting  chiefly  of  sodium  chloride  and  sodiiun  sulphate. 

Salt  Bed-In  January,  1880,  the  bed  of  the  lake  was  nearly  dry,  and  was 
explored  by  Mr.  Willard  I).  Johnson,  who  was  able  to  travel  on  foot  across 
a  bed  of  salt  where  the  water  had  before  been  deepest.  In  places  this  bed 
was  covered  by  a  thin  sheet  of  bitter  water,  but  elsewhere  its  surface  was 
dry.  It  was  rej)orted  by  persons  resident  in  the  vicinity  that  in  the  fall  of 
the  year  the  entire  area  had  been  dry,  and  that  this  condition  had  been 
attained  by  the  lake  basin  during  one  or  two  })receding  seasons.  On  the 
2()th  of  August,  the  same  year,  Mr.  Russell  and  I  visited  the  locality,  but 
the  condition  of  tlie  crust  of  salt  did  not  permit  us  to  cross  it.  It  had  prob- 
ably, in  the  interval,  ])eeu  partially  or  wholly  redissolved  and  redeposited; 
and  its  new  state  of  aggregation  was  less  compact. 

Mr.  Johnson  cut  through  the  salt  layer  at  several  points,  finding  a 
general  thickness  of  four  or  five  inches;  and  he  collected  samples  near  the 
center  of  the  area.  Another  series  of  samples  was  collected  by  Mr.  Russell 
at  the  margin  of  the  area;  and  at  each  point  the  underlying  sediments  were 
explored  to  a  depth  of  a  few  feet.     The  following  are  the  recorded  sections: 

Section  at  center  of  Sevier  Lake  salt  bat,  January,  1880. 

1.  (Top).  Sodiiiiii  sulphate,  2  inches. 

2.  Sodiuiii  sulphate  with  some  sodium  chloride  ;  coherent  to  No.  1 :  1  inch. 
15.  Sodium  sulphate,  tinged  with  pink,  2  inches. 

4.  Gray  clay  containing  woody  fil>re,  2  inches. 

5.  Fine  sand  containing  fresh  water  shells,  6  inches. 

6.  Gray  clay. 

MON   I 15 


226 


LAKE  BONNEVILLE. 


Section  at  margin  of  Sevier  Lake  salt  bed,  Anguat  20,  1880. 

1.   (Top).   Sixliiim  chloriilo,  foriiiiiij;  a  colicroiit  crust :  i  inoli. 

'.;.  Soiliiiin  chloride,  with  Hodiiim  8uli)hato  and  magnesium  sulpbato;  free  crystals  luiugled  with 
water:   li  iuclies. 

:!.   Sodium  siilph.ate,  witli  sodium  chloride  ;  a  crust  of  coherent  crystals:  i  inch. 

4.  Sodium  chloride,  with  magnesium  sulphate;  incoherent  crystals  mingled  with  water:  IJ 
inches. 

C>.  Sodium  chloride,  with  sodium  sulphate,  cliemii-ally  identical  with  No.  2  hut  (ine-Kraim-d  and 
with  the  consistence  of  an  ooze;  color  white  above  with  occasional  passages  of  pink,  green  heueath: 
i  inch. 

().  Dark  gray  mud  :  2  feet. 

Tlie  sulijoined  table  of"  analyses  exlii1)its  in  detail  the  constitution  of 
the  saline  de})osits  in  each  section,  and  the  composition  of  the  original  brine 

is  added  for  comparison.  The  con- 
spicuous fact  is  that  the  sodium  sul- 
pliate  is  concentrated  in  the  middle 
(if  the  basin,  while  the  sodium  chlo- 
ride is  chiefly  deposited  at  the  mar- 
gin. The  sulphates  of  magnesium 
and  potassium  likewise  occur  exclu- 
sively at  the  margin.  It  is  note- 
\\(»rthy  also  that  magnesium  is  re- 
ported in  larger  proportion  in  the 
Ijrine  of  the  lake  than  in  any  layer 
of  the  desiccation  products  at  either 
point  of  determination.  The  mag- 
nesium chloride  reported  in  the  brine 
implies  three  per  cent,  of  magnesium. 
The  magnesium  sulphate  in  the 
richest  layer  of  the  desiccation  prod- 

FlG.  31.— Sevi.r  L,iko  in  1873  (Nell).    The  white  areas    uct     impHeS     Oldy     1.7     per     Ceut.     of 
with  dotted  biniuduriu.s  show  ealt  bods  in  1880  (JoIidbou). 

magnesium. 
The  brine  of  the  lake  was  analyzed  by  Dr.  Oscar  Loew;  the  desicca- 
tion products  from  the  center  of  the  area  by  Prof  S.  A.  Lattimore;  those 
fit  mi  tlie  margin  by  Prof  O.  D.  Allen.  The  brine  contained  8.G4  per  cent, 
of  saline  matter;  the  constituents  are  here  reported  in  percentages  of  total 
solid   matter.     The   constituents   of  the   desiccation   products  are  likewise 


DRYING  OF  SEVIEK  LAKE. 


227 


reported  in  percentages.  The  figures  for  tlu^  total  deposit  are  obtained  by 
combining  tliose  of  tlie  separate  layers,  making  allowani'e  for  n^lative 
thickness. 

A  few  weeks  after  our  oljservation  of  tlie  salt  bed,  Mr.  Uusscll  and  I 
separately  visited  the  southern  portion  <if  tlie  lake  bottom,  where  the  water 
had  been  comparatively  shallow.  Near  the  old  shore,  and  especially  at  the 
extreme  southern  end,  the  b<»tt(»m  had  the  ordinary  [)laya  character,  a  fine 
earth,  highly  charged  with  salt,  for  the  most  part  firmly  compacted,  but  in 
places  softened  l)y  efflorescence.  Farther  from  shore  a  thin  crust  of  salt 
rested  on  a  saline  nnul,  and  at  the  outermost  point  reached  by  Mr.  Russell 
the  superficial  salt  deposit  had  a  thickness  of  1-^  inches,  consisting  chiefly  of 
a  moist,  incoherent  aggregation  of  crystals.  Beneath  this  were  greenish 
mud  and  sand. 

Table  VI.  Analyses  of  Sevier  Lake  DesiccaHon  Products  and  Brine. 


CoDstitiients. 

Desiccation  Products  at  Center. 

Desiccatiou  Products  at 

Margin. 

Solid 
contents 
of  Brine. 

Upper 
lajer. 

Second 
layei . 

Third 

layer. 

Total. 

Upper 
la>  er. 

Second 
layer. 

Third 
layer. 

Fourth 
layer. 

Fifth 
layer. 

Total. 

Sodinm  Sulphate 

Sodium  Carbonate 

Sodinm  Chloride 

Calcium  Sulphate 

Ma^nesiun)  Sulphate  .. 
Ma^ueBium  Clilorido  .. 

87.65 

1.08 

2.34 

trace 

trace 

71.23 

89.10 

84.6 
.4 

7.0 

4.78 

5.51 

83.79 

2.71 

5.04 

14.3 

15.5 

23.86 
trace 
trace 

2.65 

91.39 

trace 

1.83 

79.86 
7.83 

13.84 

trace 

1.33 

88.49 
5.29 

80.62 
.39- 
8.32 

75.8 
5.5 

72.1 
.5 

11.9 

Potassium  Sulphate  . . . 

trace 

.34 

.26 

.11 

4.03 

trace 

trace 

.92 

.68 

.7 

Boric  Acid 

Water   

8.90 
trace 

4.90 
trace 

8.20 
trace 

8.0 

2.00 

6.46 

.78 

3.40 

3.6 
.1 

Total   ... 

99.97 

99.08 

99.95 

100.0 

100,  00 

100.00 

100.  00 

100.00 

100.  00 

100.  00 

100.  00 

The  desiccation  of  this  lake  is  to  be  ascribed  to  human  agency.  The 
water  of  its  sole  tributary  flows  for  nearly  200  miles  through  valleys  con- 
taining more  or  less  arable  land,  and  has  gradually  been  monopolized  by 
the  agriculturist  for  the  purpose  of  irrigation.  The  supply  is  however  not 
completely  cut  off.  It  is  reported  that  during  the  spring  freshets,  caused  by 
the  melting  of  the  snow  on  the  plateaus  and  mountains,  the  lake  bottom 
receives  considerable  inflow,  and  that  the  desiccated  condition  obtains  dur- 
ing only  a  portion  of  the  year. 

The  principal  salt  deposit  was  estimated  to  extend  eight  miles  north 
and  south  and  to  have  an  extreme  width  of  about  five  miles.     The  accom- 


228  LAKE  BONNEVILLE. 

panying  sketch  shows  the  form  and  area  of  the  lake   iu   1872   and  the 
approximate  extent  and  position  of  the  salt  beds  iu  1880. 

RUSH  LAKE. 

The  lowest  depression  of  Rush  Valley  contains  a  pond  or  lakelet  which 
has  been  observed  to  undergo  considerable  fluctuation.  It  will  be  recalled 
that  Rush  Valley  in  pre-Bonneville  time  drained  freely  to  Tooele  Valley 
and  that  this  drainage  was  cut  off  by  an  embankment  built  by  the  Bonne- 
ville waves.  The  lake  occupies  a  portion  of  the  old  drainage  channel  close 
to  the  embankment.  It  is  partially  delineated  in  the  map  on  PI.  XX.  The 
earliest  record  of  it  appears  on  Stansbury's  map  (1850)/  but  it  is  not  men- 
tioned in  his  text.  It  is  there  assigned  a  length  of  about  1^  miles,  but  there 
is  circumstantial  evidence  that  no  measurement  was  made.  In  1 855  it  was 
included  in  a  military  reservation  laid  out  by  Lieut.  Col.  E.  J.  Steptoe  for 
the  purpose  of  securing  to  the  military  post  at  Camp  Floyd  the  meadow  and 
pasturage  about  the  lake  shore.  The  map  made  for  the  purpose  of  defining 
the  reservation,  assigned  to  the  lake  a  length  of  2|  miles,  and  indicated  that 
the  water  was  shallow  and  marshy.  The  land  surveys  in  the  valley  in 
1856  did  not  include  the  military  reservation,  but  showed  the  existence  upon 
it  of  a  lake.  According  to  Gen.  P.  E.  Connor,  who  succeeded  Col.  Steptoe 
in  18G2,  there  was  then  only  a  small  pond,  the  remainder  of  the  lake  bed 
being  occupied  by  meadow  land.  In  18G5  the  water  began  to  increase,  the 
greatest  height  being  attained  in  187G  or  1877,  since  which  time  it  has  sub- 
sided. The  rise  of  the  water  submerged  the  meadow  land  and  rendered 
the  reservation  useless  for  its  original  purpose.  It  was  therefore  ofticially 
relinf[uished  by  the  War  Department  in  1869. 

In  1872,  the  water  being  near  its  highest  stage,  the  lake  was  surveyed 
in  connection  with  the  surrounding  country  by  one  of  the  parties  of  the 
Wheeler  Survey,  and  the  length  was  determined  to  be  4^  miles. 

In  1880,  Avhen  the  lake  was  visited  by  the  writer,  it  was  said  l)y  residents 
to  have  shrunken  to  half  its  ninximuni  size.     The  position  of  the  highest 


'  Expl.  ami  Siirv.  V;i]lc<y  of  the  Groat  Sail  Lake  of  Utah.     By  Howard  Stausbury,  Capt.  Corns 
Topof,'.  ling.,  U.  S.  A.     I'hilaclclphia,  1852. 


FRESBNESS  OF  RUSH  LAKE.  229 

shore-line  was  not  pointed  out,  but  it  is  believed  to  be  represented  at  the 
north  end  by  a  fresh  looking  beach,  not  yet  covered  by  vegetation.  Tliis 
beach  had  a  lieight  above  the  water  surface  of  10  feet.  The  greatest  depth 
of  the  water  was  ascertained  to  be  5^  feet. 

At  no  time  does  the  lake  appear  to  have  been  strongly  saline.  Diu-ing 
its  highest  stage  it  was  so  fresh  as  to  serve  not  only  for  the  watering  of 
stock  but  for  domestic  use;  and  in  1880  it  was  far  from  being  undrinkable, 
though  too  brackish  to  be  palatable.  Its  mineral  contents,  judged  by  the 
taste,  did  not  exceed  one-half  of  one  per  cent.  This  freshness  stands  in 
strong  contrast  to  the  salinity  of  the  Snake  Valley  salt  marsh  and  Sevier 
Lake,  yet  the  conditions  are  in  most  respects  nearly  identical.  Each  of  the 
three  lakes  is  the  evaporating  pan  for  a  closed  basin;  and  each  basin  in- 
cludes a  valley  plain  sheeted  with  Bonneville  sediments,  everywhere  more 
or  less  saliferous.  The  salinity  of  Sevier  Lake  and  the  salt  marsh  is  thus 
easily  accounted  for,  and  only  the  freshness  of  Rush  Lake  is  problematic.  I 
conceive  that  the  true  explanation  lies  in  the  hypothesis  of  burial  by  desic- 
cation, already  advanced  to  account  for  an  element  of  the  Bonneville  history. 
At  some  period,  or  at  several  different  periods,  the  lake  has  evaporated  to 
dryness;  and  its  saline  matter  being  thus  precipitated  has  become  buried 
beneath  mechanical  sediment.  The  last  period  of  this  kind  was  so  recent 
that  the  subsequent  accumulation  of  saline  matter  has  not  given  a  briny 
character  to  the  water. 

If  this  hypothesis  is  true,  then  Sevier  Lake,  having  by  the  settlement 
of  the  Sevier  Valley  been  changed  from  a  perennial  lake  to  an  occasional 
lake  or  playa  lake,  should  in  the  course  of  time  lose  its  saline  character. 
Every  freshet  of  the  Sevier  River  which  carries  niechanical  sediment  to  the 
lake  but  does  not  pour  into  it  a  sufficient  body  of  water  to  redissolve  the 
precipitated  salt,  must  mingle  -with  that  salt  a  certain  amount  of  silt,  and 
the  continuance  of  the  process  will  have  the  effect  of  obstructing  and  finally 
of  preventing  the  access  of  the  water  to  the  salt.  The  lake  liottom  will  then 
be  reduced  to  the  condition  of  an  ordinary  playa,  and  should  some  political 
or  industrial  revolution  afterward  stop  the  work  of  irrigation  in  the  ■salley 
of  the  Sevier  and  permit  the  lake  to  be  restored,  the  water  of  the  lake  will 
at  first  be  fresh. 


230  LAKE  BONNEVILLE. 


GREAT  SALT  LAKE. 

The  present  investigation  has  added  Httle  to  our  knowledge  of  Great 
Salt  Lake.  It  Avas  part  of  the  original  plan  to  give  to  it  a  somewhat  elal)- 
orate  study,  ascertaining  the  distribution  of  high  and  low  salinity  within  its 
area,  the  nature  of  the  deposits  formed  in  various  parts  of  its  bed,  and  the 
economic  properties  of  its  brine.  It  was  proposed  also  to  make  a  thorough 
survey  of  its  bottom,  so  as  to  ascertain  the  presence  or  absence  of  sul)merged 
shore-lines  and  jjlayas.  These  inquiries,  having  been  deferred  until  the  end 
of  the  Bonneville  investigation  proper,  were  necessarily  abandoned  when  it 
was  decided  to  bring  that  work  to  an  immediate  close.  Fortunately,  the 
lake  received  careful  attention  at  the  hands  of  earlier  expeditions  and  sur- 
veys, and  its  history  is  already  as  well  known  as  that  of  auy  other  inland 
lake,  with  the  possible  exception  of  the  Dead  Sea  and  the  Caspian. 

surveys.-It  wMs  survcyod  and  mapped  by  Stansbury  in  the  years  1849 
and  IS."")!).  It  was  again  map})ed  by  the  Fortieth  Parallel  Survey  in  ISCS, 
and  the  data  for  a  third  map  have  since  been  gathered  by  the  Survey  West 
of  the  lOOtli  Mendian.  In  connection  with  the  first  and  second  of  these 
surveys  analyses  were  made  of  the  brine,  and  the  first  and  third  ran  nu- 
merous lines  of  sounding.  Additional  data  of  value  were  gathered  by  Fre- 
mont in  1843  and  by  various  parties  of  the  Wheeler,  Ilayden,  and  Powell 
surveys.  As  a  member  of  the  PoAvell  Survey,  the  wnter  made  a  study  of 
the  recent  oscillations  of  the  lake;  and  a  system  of  records  by  means  of 
gauges,  instituted  at  that  time,  h;is  ])een  continued  by  the  U.  S.  Geological 
Survey. 

Depth.  Tluf  most  striking  feature  of  the  hydrography  of  the  lake  is  its 
shallowness.  The  soimdings  taken  by  Stansl)ury  indicate  a  mean  deptli,  in 
18.0(),  of  nbout  thirteen  feet;  and  although  the  height  of  the  wnter  .surfnce 
afterward  rose  fully  ten  feet,  the  rise  was  accompanied  by  the  additimi  of 
such  large  ;ireas  of  slinllow  water  that  the  mean  depth  was  increased  less 
than  .''»  feet.  Tlie  iiiaxiiiuiiii  (lej)th  reported  by  Stansbury  is  3(5  feet,  and  at 
the  highest  stage,  49  feet  of  water  was  found  near  tlie  same  place. 

Gauging.-In  1875  the  first  definite  determination  of  the  lake  level  was 
made,  and  since  that  time  a  nearly  continuous  record  of  its  oscillations  has 


DEPTH  OF  GEEAT  SALT  LAKE.  231 

been  kejit.  A  less  accurate  knowledge  of  the  change  of  level,  Ijased  in 
part  on  tradition,  extends  back  to  1845.  In  the  following  account  of  tlu; 
oscillations,  the  direct  observations  will  be  first  described,  and  afterward  the 
indirect  determinations. 

In  the  year  1875,  Dr.  John  R.  Park,  of  Salt  Lake  City,  at  the  sugges- 
tion of  Prof.  Joseph  Henry  of  the  Smithsonian  Institution  and  with  the  co- 
operation of  other  citizens,  instituted  a  series  of  observations.  There  was 
erected  at  the  water's  edge  at  Black  Rock  a  granite  Idock  cut  in  the  form  of 
an  obelisk  and  engraved  on  one  side  with  a  scale  of  feet  and  inches;  and 
Mr.  John  T.  Mitchell  was  engaged  to  observe  the  water-height  at  intervals 
of  a  few  days.  In  1877  Mr.  Jacob  Miller  of  Farmington,  at  the  instance 
of  the  writer,  erected  near  that  place,  in  a  slough  connnunicating  with  the 
lake,  a  post  of  wood  graduated  to  inches.  Upon  this  gauge  a  record  was 
begun  in  November,  1877.  In  the  course  of  time  the  lake  fell  so  low  that 
its  water-level  could  not  he.  determined  by  either  of  these  gauges,  and  in 
1879  a  third  was  set  up  by  Mr.  E.  Garn  at  the  bathing  resort  known  as 
Lake  Shore.  The  Lake  Shore  gauge  consisted  of  a  wooden  pile  driven  into 
the  clay  bed  of  the  lake  and  engraved  with  a  scale  of  feet  and  inches.  The 
continued  recession  of  the  water  rendering  it  apparent  that  this  gauge  also 
would  eventually  become  useless,  the  U.  S.  Geological  Survey  in  1881  es- 
tablished a  fourth  gauge  at  Garfield  Landing,  a  short  distance  west  of  Black 
Rock.  It  consisted  of  a  red-wood  jdank,  with  a  scale  of  feet  engraved 
and  painted,  spiked  to  a  ]»ile  of  the  steamboat  wharf  at  thnt  point.  The 
Survey  also  ascertained  th  relative  height  of  the  zeros  of  all  the  gauges; 
and  as  none  of  them  were  of  a  permanent  nature,  it  connected  them  by 
leveling  with  a  durable  l)ench-mark  set  out  of  the  reach  of  the  waves  of 
the  lake. 

The  Black  Rock  bench,  as  it  will  be  convenient  to  call  it,  consists  of  a 
granite  post  about  three  feet  in  length,  sunk  in  the  earth  all  )>ut  a  few  inches, 
on  the  northern  slop<^  of  a,  small  limestone  knoll  just  south  of  the  railroad 
track  at  Black  Rock.  Its  top  is  dressed  square,  al)out  10  by  10  inches,  and 
is  marked  with  a  -f .  A  sketch-map  (PI.  LI)  was  made  of  the  locality  in 
1877,  at  the  time  of  the  establishment  of  the  bench,  and  it  is  hoped  that 
this  will  serve  for  its  identification  at  any  future  time. 


232  LAKE  BONNEVILLE. 

Observations  of  lake  level  were  made  on  tlie  IJlack  Rock  gauge  troiu  Sep- 
tember, 1875,  to  October,  1876,  and  single  observations  were  made  in  July 
and  October,  1877.  The  P'armington  gauge  was  used  from  November,  1877, 
t(i  November,  1879;  the  Lake  Shore  gauge  fmiii  November,  1879,  to  Sep- 
tember, 1881 ;  the  Garfield  Landing  gauge  from  Api-il,  iSSl,  to  June,  iSSd. 

The  Garfield  Landing  gauge  was  inspected  l)y  mcml)ers  of  tlic  corps 
from  time  to  time  until  1884,  when  Salt  Lake  City  ceased  to  ))e  a  base  for 
field  operations.  In  1886  Prof.  Marcus  E.  Jones  of  that  city  ascertained 
and  reported  that  the  gauge  had  suffered  accidents  wlierel>y  its  zero  liad 
been  raised  three  tir  four  inches,  but  the  dates  of  change  were  not  learned. 
In  June  of  the  same  year  it  was  destroyed  by  a  storm.  Prof.  Jones  then 
began  observations  of  the  water  height,  and  eventually  prepared  and  in- 
stalled a  new  gauge,  placing  it  near  the  position  of  the  old  one  at  Garfield 
Landing,  and  fixing  its  zero  at  the  same  height.  This  gauge,  which  will  1  le 
called  the  New  Garfield,  is  still  in  use. 

All  of  the  gauges  except  the  New  Garfield  have  by  various  accidents 
become  displaced,  so  that  the  authenticity  and  coherence  of  the  i-ecords 
depend  wholly  on  the  leveling  and  other  observations  conducted  tt)  deter- 
mine the  relative  heights  of  the  gauge  zeros.  Connection  between  the 
Farmington  and  Lake  Shore  gauges  was  established  by  the  writer  by  spirit- 
level  at  the  time  of  the  institution  of  the  latter  gauge.  The  Lake  Shore 
and  Garfield  Landing  gauges,  which  are  separated  by  a  space  of  more  than 
20  miles,  were  observed  simultaneou.sly  for  a  period  of  five  days  in  March, 
1881,  the  lake  being  at  the  time  little  disturbed  by  wind.  In  1877  the  late 
Mr.  Jesse  W.  Fox  and  the  writer  ran  levels  from  the  Black  Rock  "■iiuffe  to 
tlie  Hlack  Rock  bench;  and  in  1881  Mr.  Russell,  by  the  aid  of  the  .s])irit- 
level  and  the  level  aff"orded  by  the  calm  lake  surface,  connected  the  Garfield 
gauge  in  like  manner  with  the  Black  Rock  bench. 

These  various  determinations,  together  with  others,  have  been  compiled 
and  reduced  to  a  system  by  Mr.  Wel)ster,  Avhose  report  on  the  hypsometric 
work  performed  in  connection  with  the  Boimeville  investigation  will  be 
found  in  Appendix  A.  He  has  selected  the  zero  of  the  Lake  Shore  gauge 
as  the  datum  or  reference  point  for  all  heights  within  the  basin.  I  insert  a 
table  of  gauge  heights  based  on  liis  compilation. 


GAUGING  GREAT  SALT  LAKE. 


233 


Tablk  VII.  Datum  PoUtts  coiincvttd  with  iht  gaiiyitnj  of  Great  Salt  Lake, 


lilack  Rock  Bencli 

Kiirminston  Beuch 

lihick  Itock  Gau{:;e  Zt^ro. . 
Farniiugton  Gauj;o  Zero  . , 
Lake  Shore  Gaiifje  Zero  . 

Garticld  Gauge  Zero 

New  Garfield  Gauge  Zero 


Feet. 

+41.8 

+  1G.  7 

+  5.3 

+  3.K 

0.0 

-  4.0 

-  4.6 

Oscillations  since  i875.-Tlie  followiug'  ta])le  sliows  iill  tlie  trustwoi'tliy  obsei'va- 
tions  recorded  by  the  observers  at  these  several  stations.  It  does  not  cover 
the  entire  i)eriod  from  1875,  but  the  breaks  are  unimjxirtant. 

Table  VIII.  Record  of  Oscillations  of  Great  Salt  iMke. 


Referred 

Gauge. 

Observer. 

Year. 

Day. 

Keatling. 

to  Lake 
Shore 
Zero. 

Ft.     In. 

Feet. 

lilack  Eock 

J.T.  Mitcliell... 

1875 

Sept.  14 

0     0 

5.8 

22 

0     5i 

5.7 

25 

0     5 

5.7 

Oct.      0 

0    4i 

5.0 

12 

0     4 

5.0 

18 

0   :ii 

5.0 

20 

0     3 

5.5 

Xov.    9 

0     2 

5.4 

10 

0  n 

5.4 

23 

0     4 

5.6 

29 

0    .-.i 

5.7 

Dec.     7 

0     5 

5.7 

14 

0     51 

5.7 

21 

0     6 

6.8 

1870 

.Ian.      5 

0     8 

5.9 

11 

0     K* 

0.0 

29 

0     9 

6.0 

Feb.     1 

0     9 

0.0 

15 

0   95 

6.1 

22 

0    9i 

6.1 

Miir.  15 

0     11 

0.2 

22 

1     0 

6.3 

28 

1     04 

0.3 

Apl.    17 

1     2 

6.4 

25 

1     3 

6.5 

May     2 

1     4 

6.6 

22 

1     9 

7.0 

J"une    2 

1     11 

7.2 

8 

2    0 

7.3 

13 

2    2 

7.4 

- 

23 

2    4 

7.6 

234 


LAKE  BONNEVILLE. 


Table  VIII.  Record  of  Oacillationa  of  Great  Sail  Zaic— Continued. 


Ileforred 

(r.anKo. 

Observer. 

Year. 

Day. 

Reading 

to  Lako 
Shftre 
Zero. 

Fl.    In. 

Feet. 

m.vk  Kork 

J.T.  Mitchell  . 

1876 

Juno  30 

2     6 

7.8 

July   18 

2     3 

7.5 

25 

2     4 

7.0 

Auk.     1 

2    3 

7.5 

10 

2    2 

7.4 

22 

1     9 

7.0 

20 

1    8 

0.9 

30 

1     8 

B.  9 

.Sept.  14 

1    7 

6.9 

10 

1     6i 

0.8 

2G 

1     6 

6.8 

Oct.      0 

1     51 

6.7 

G.  K.  Gilbert  .. 

1877 

July   12 

2    0 

7.3 

Oct.    19 

0     10 

6.1 

Nov.  24 

2    1 

5.8 

Farmington 

.T     Mlllor 

1878 

Jan.    21 

2    li 
2    2i 

5.9 

Mcli.  28 

6.0 

May 

2    5 

0.2 

June  .10 

2    C 

6.3 

July  18 

2    3J 

6.1 

Nov.     1 

1     0 

4.8 

Doc.    11 

0    11 

4.7 

1870 

May     2 

1    4 

5.0 

Lake  ehoro 

E.  Gam 

Nov.  19 
Doc.     2 

2    6 
2    C 

2.5 
2.5 

10 

2    7J 

2.B 

31 

2    9 

2.7 

1880 

Jan.   14 

2    9J 

2.8 

29 

2    7J 

2.6 

Fob.  23 

2    7J 

2.6 

Mar.  10 

2    9i 

2.8 

30 

2     10 

2.8 

Apr.  15 

2  lO.i 

2.9 

28 

2  Il.i 

3.0 

May    12 

3     1 

3.  1 

2fi 

3    3.5 

3.3 

Juno  10 

3    4 

3.3 

28 

3    4i 

3.4 

July  13 

3     3« 

3.3 

30 

3     1 

3.1 

Aug.  U 

2     11 

2.9 

29 

2     8 

2.7 

Sept.  14 

2    5 

2.4 

20 

2    2 

2.  2 

Oct.     15 

1  ll.i 

2.0 

29 

1   lOJ 

1.9 

Nov.  12 

1     9 

1.7 

29 

1    8i 

1.7 

Doc.    11 

1    8J 

1.7 

14 

1     9 

1.7 

RISE  AND  FALL  OF  GREAT  SALT  LAKE. 


235 


Table  VIII.  Record  of  Oscillations  of  Oreat  Salt  Lake — Continued. 


Referred 

Gauge. 

Observer. 

Tear. 

Day. 

Reading. 

to  Lake 
Shore 
Zero. 

Ft.    In. 

Feet. 

Lake  ^horo 

E.  Garn 

1«80 
.    1S81 

27 
Jan.    U 

1    10 
I    10 

1.8 
1.8 

28 

2    2 

2.2 

Fob.   14 

2     0 

2.5 

28 

2    6i 

2,5 

Mar.  14 

2    7J 

2.0 

Garfield  Landing  . . . 

T.  Douris 

Apr.     1 

7    3 

2.6 

16 

7    4J 

2.7 

May     1 

7    8 

3.0 

16 

7     11 

3.3 

Juno    1 

8    0 

3.4 

10 

8    OJ 

3.4 

July     1 

7  lOJ 

3.2 

16 

7     10 

3.2 

23 

7     9 

3.1 

Aug.    2 

7     6 

2.9 

19 

7    4 

2.7 

Sopt.     8 

7    0 

2.4 

10 

0    n 

2.3 

Oit.      2 

0    9 

2.  1 

10 

6    9 

2.1 

Nov.     2 

0    8 

2.0 

10 

6     8 

2.0 

Die.     1 

0    8 

2.0 

15 

6     !l 

2.1 

lKS-2 

Jan.     2 

6     0 

2.1 

' 

16 

0    10 

2.2 

Fob.      2 

6  inj 

2.2 

10 

6     11 

2.3 

M;ir     2 

0  IIJ 

2.3 

21 

7     OJ 

2.4 

A  pi.      1 

7  n 

2.0 

IB 

7   ;i 

2.0 

May     2 

7     5 

2.8 

16 

7    0 

2.9 

June    2 

7    OJ 

2.9 

10 

7     0 

2.9 

July     2 

7     4 

2.7 

17 

7     24 

2.0 

Aug.    2 

7    0 

2.4 

15 

6     10 

2  2 

Sei>t.    2 

0    5 

1.8 

10 

6    3 

1.0 

Oot,.      2 

6     IJ 

1.5 

l.'i 

6     0 

1.  4 

IVc.    l.--. 

0     0 

1  4 

30 

0     0 

1.4 

18K3 

Jan.    15 

6     0 

1.4 

1 

30 

0     0 

1.4 

236 


LAKE  BONNEVILLE. 


Taiilk  VIII.  Record  of  Oscillationn  of  Great  Salt  Lake — Continued. 


Koferroil 

Gauge. 

Obsi-rvi-r. 

Tear. 

Day. 

Heading. 

to  Lak. 
Sliun- 
Zero. 

Ft.     In. 

Feet. 

(lai'tii^lil  Landing      .. 

T.  Oiiuris 

IKHI 

Feb.    ir, 

G    1 

1.5 

.-SO 

0    H 

1.5 

Mar.  15 

G    2 

1.5 

A  pr.     2 

G    4 

1.7 

Si-]it,   :i 

0     0 

1.9 

10 

0     2 

1.5 

Oi:t.       3 

5    8 

1.0 

IS 

5    5 

O.R 

Nov.      1 

5     3 

O.G 

15 

5     0 

0.4 

Doe.     2 

5     0 

0.4 

15 

5     0 

0.4 

I8K4 

Jan.     2 

5     0 

0.4 

15 

5    Oi 

0.4 

Feb.     2 

8    OJ 

0.4 

15 

5     IJ 

0.5 

Mar.     1 

5    2J 

0.6 

15 

5    6 

0.9 

Apr.     1 

5     8 

1.0 

15 

5  11 

1.3 

May     2 

G    2 

1.6 

15 

0     5 

1.9 

June    1 

7    0 

2.4 

15 

7    3 

2.6 

July     1 

7    5J 

2.8 

15 

7    5J 

2.8 

Aug.    2 

7    2J 

2.6 

15 

7    OJ 

2.4 

Sept.    1 

7    0 

2.4 

15 

7     0 

2.4 

Oct.      2 

7     0 

2.4 

15 

G  11 

2.3 

Nov.     1 

6  11 

2.3 

15 

6  10 

2.2 

Doc.      2 

0  1(1 

2.2 

15 

0  11 

2.3 

1885 

Jan.     2 

7     1 

2.5 

15 

7    2* 

2.6 

Feb.     2 

7    3i 

2.7 

IG 

7    5 

2.8 

Mar.    2 

7    6 

2.9 

16 

7    8J 

3.1 

Apr.    3 

7  10 

3.2 

10 

7  U 

3.3 

May     2 

8     1 

3.5 

15 

8    3 

3.0 

June    1 

8     G 

3.9 

IG 

8    9 

4.1 

July     2 

8  10 

4.2 

15 

8  n 

4.2 

lilSE  AND  FALL  OF  GliEAT  SALT  LAKE. 

Tablk  VIII.  Itecord  of  OscillaHoiis  of  Great  Salt  toAe— Continued. 


237 


Gauge. 

Observer. 

Year. 

Day. 

Reading 

Referred 

to  Lake 

Shore 

Zero. 

<larfielil  Lauding 

T.  Duuri.s 

1885 

Aug.    2 

15 
Si-iit.    2 

15 
Oct.      2 

15 
Nov.     1 

15 
Die.      2 

15 

Ft.     In. 

8    8 
8     7 
8     3 
8     0 
8    0 
7  llj 
7  11 
7     9 
7     9 
7  11 

Feet. 
4.0 
4.0 
3.0 
3.4 
3.1 
3.3 
3.3 
3.1 
3.1 
3.3 

IKfG 

Jan.      2 

15 
Feb.     2 

15 
Mar.    2 

15 
Apr.     1 

15 
May     2 

15 

8     0 
8     1 
8     35 
8     5 
8     7 
8     9 
8  10 

8  11 

9  0* 
a    I 

3.4 
3.5 
3.7 
3.8 
4.0 
4  1 
4.2 
4.3 
4.4 
4.5 

New  Garfield .... 

M.  E.  JoHOs 

June    2 
July  20 

9    2.i 
8  lOJ 

4.6 
4.2 

Oct.      2 

8     2 

3.6 

Nov.     C 

8    0 

3.4 

Dec.   28 

8     2J 

3.6 

1887 

Feb.     5 
Mar.     5 

19 
Apr.    2 

10 
May     7 

22 

30 

8     H 
8     4 
8     5J 

6  n 

8     6J 
8     5i 
8    Kj 
8    8i 

3.5 
3.7 
3.8 
3.8 
3.9 
3.8 
4.1 
4.1 

June  10 
June  22 
July     4 

14 
Aug,    0 
.Scjil.    5 

20 
O.t.      4 

25 
Nov.  11 

8    8i 
8    7J 
8     f.J 
8    55 
8     IJ 
7    Si 
7    41 
7    3i 
7     IJ 
7     1 

4.1 
4.0 
3.9 
3.8 
3.5 
3.1 
2.7 
2.7 
2.5 
2.5 

1888 

Jati.     I 
10 

Feb.     1 
24 

Mar.     3 
23 

Apr      6 

7     1 
7     2J 
7     3 
7     4 
7    4 
7     (ij 
7    7 

3.5 
2.6 
2.6 
2.7 
2.7 
2.9 
3.0 

238 


LAKE  BONNE VI LLK. 


Tablk  VIII.   Jiccurd  of  Oacillalioiu  of  Great  Salt  Lake — Coutiuiioci. 


Rtf.rroil 

Gauge. 

ObsHiver. 

Y.-ivi. 

Day. 

Ueailiii;;. 

til  I.akii 
SImre 

Zfle. 

/•Vrf. 

Ft.     In. 

New  Gartield  

M.  E.  Jonea 

IMS 

May     8 

7    5 

2.8 

30 

7    53 

2.9 

.lurni  22 

7    34 

2.7 

July     3 

7     U 

2.5 

23 

.6    9 

2.2 

An;;.    1 

0    8 

2.1 

16 

0    G 

1.9 

Si.pt.    1 

6    4 

1.7 

15 

«    u 

l-.l 

Oct.      1 

5  11 

1.3 

Nov.     1 

5     5 

0.8 

10 

5    7 

1.0 

~- 

Dec.    10 

5    7 

1.0 

1889 

Jan.      1 

5    7 

1.0 

16 

5     7 

1.0 

Feb.     1 

5    8 

1.1 

15 

5    9 

1.2 

Mar.    1 

6    0 

1.4 

25 

6     1 

1.6 

Apr.  15 

5    9 

1.2 

May     1 

5  n 

1.3 

20 

5    9 

1.2 

June    1 

5    8 

1.1 

25 

5    5 

0.8 

July  12 

4  11 

0.3 

Aug.  10 

4    0 

-0.1 

30 

4     IJ 

-0.5 

Sept.  23 

3    7 

—1.0 

Oct.    12 

3    71 

-1.0 

Dec.    14 

3    8 

—0.9 

1890 

Jan.     4 

3    9 

—0.8 

An  examination  of  tliese  observations,  or  of  the  curve  plotted  frftm 
tlieni,  shows  that  the  osciUations  fall  readily  into  two  classes;  the  one  peri- 
odic, completing  its  cycle  in  12  months;  the  other  non-periodic.  The  curve 
in  Figure  32  shows  the  nature  of  the  annual  oscillation,  being  derived  from 
the  records  of  eight  complete,  though  not  consecutive,  years.  Three  periods 
were  used:  October  1,  1875,  to  October  1,  187G;  Jaiuiary  1,  18S0,  to  Jan- 
uary 1,  1883;  and  November  1,  1883,  to  November  1,  18S7.  Tlu'  curve 
has  a  single  maximum,  falling  near  the  summer  solstice,  and  a  single  iiiiui- 
mum,  foiling  five  months  later.  The  maximum  is  more  acute  than  the 
minimum.     The  range  is  IG  inches.     The  rise  occupies  seven  months  and 


THE  ANNUAL  RISE  AND  FALL. 


289 


the  fall  only  five,  but  the  most  rapid  change  is  that  portion  of  the  rise  oc- 
cuiTiug  in  May. 


JAN 

nre 

MAR 

ARL 

MAY 

JUN 

JUL 

AUG 

SEP 

OCT 

NOV 

de:c 

/ 

N 

^ 

/ 

\ 

^ 

^ 

\ 

__^ 

-fee6 

/  s 


/■O 


OS 


Fill.  32— Annual  Kise  and  Fall  oftlio  watur  suil'ace  of  Great  Salt  Lake. 

The  cause  of  this  annual  variation  is  at  once  apparent.  The  chief 
accessions  of  water  to  the  lake  are  from  the  melting  of  snow  on  tlie  mount- 
ains, and  this  occurs  in  the  spring,  occasioning  the  rise  of  the  water  from 
March  to  June.  Water  escapes  from  the  lake  only  by  evaporation,  and 
evaporation  is  most  rapid  in  sunnner.  Before  the  influx  from  melting  snow 
has  ceased,  it  is  antagonized  by  the  rapidly  increasing  evaporation;  and  as 
soon  as  it  ceases,  the  surface  is  quickly  lowered.  In  the  autunm  tlie  rate  of 
evaporation  gradually  diminishes;  in  November  it  barely  equals  the  tribute 
of  the  spring-fed  streams;  and  In  winter  it  is  overpowered  by  such  aqueous 
product  of  mountain  storms  as  is  not  stored  up  in  snow  banks. 

It  cannot  be  doul)ted  that  the  nature  of  the  annual  oscillation  is  modi- 
fied by  the  diversion  of  water  for  irrigation,  but  an  attempt  to  discover  the 
modification  failed.  As  the  irrigation  area  steadily  increased  during  the 
time  covered  by  the  gauge  records,  it  was  conceived  that  the  influence  of 
irrigation  might  become  apparent  if  curves  were  separately  derived  from 
the  earlier  records  and  the  later,  but  it  was  found  that  neither  the  curve 
deduced  from  four  years  of  record  between  1875  and  1883  nor  the  curve 
deduced  from  four  years  of  record  from  1883  to  1887  difl"ered  materially 
from  the  curve  based  on  the  whole  eight  years. 

Observations  prior  to  1875— TuHiiug  uow  to  tlie  iudircct  determination  of  oscil- 
lations prior  to  1875,  we  have  a  collection  of  circumstantial  and  traditionary 
data  which  sufficiently  indicate  the  general  nature  of  the  non-periodic  oscil- 
lations since  the  year  1845. 


240  LAKE  BONNEVILLE. 

From  1847  to  the  present  time  the  ishmds  of  the  lake  have  been  used 
as  herd  grounds.  Fremont  and  Carrington  islands  have  l)een  reached  by 
boat,  and  Antelope  and  Stansbury  islands  partly  by  boat,  partly  by  fording, 
and  partly  by  land  communication.  A  large  share  of  the  navigation  has 
been  performed  by  citizens  of  Farmington,  and  the  shore  in  that  neiglibor- 
hood  is  so  flat  that  changes  of  water  height  have  necessitated  frequent 
changes  of  landing  place.  The  pursuits  of  the  boatmen  were  so  greatly 
affected  that  all  of  the  more  important  fluctuations  were  impressed  upon 
their  memories;  and  most  of  the  changes  were  so  associated  \vith  features 
of  the  to})ograpliy  that  some  estimate  of  their  quantitative  values  could  be 
made.  The  data  which  thus  became  available  were  collated  for  the  late 
Professor  Henry  by  Mr.  Jacob  Miller,  a  resident  of  Farmington,  who  took 
part  in  the  navigation.  His  results  agree  very  closely  with  those  derived 
from  an  independent  investigation  of  my  own,  which  has  already  been  re- 
corded in  an  essay  on  the  Avater  sup])ly  of  Great  Salt  Lake,  constituting 
Chapter  IV  of  Powell's  "Lands  of  the  Arid  Region."  The  following  pai-a- 
graplis  are  transcribed  with  little  change  from  that  volume. 

Antelope  Island  is  connected  with  the  delta  of  the  Jordan  River  by  a 
broad,  flat  sand  bai-  tliat  has  lieen  usually  submerged  but  occasionall\-  ex- 
posed. It  slojjcs  very  gently  towards  the  island,  and  jiist  where  it  joins  it, 
is  interrupted  by  a  narrow  channel  a.  few  inches  in  depth.  For  a  number 
of  years  this  bar  afforded  the  means  of  access  to  the  island,  and  many  per- 
sons traversed  it.  By  combining  the  evidence  of  such  persons,  the  condi- 
tion of  the  ford  has  lieen  ascertained  up  to  the  time  of  its  final  aliandon- 
ment.  From  1847  to  1850  the  bar  was  dry  during  the  low  stage  of  each 
winter,  and  in  summer  covered  by  not  more  than  20  inches  of  water.  Tlien 
began  a  rise,  which  continued  until  1855  or  185fi.  At  that  time  a  horseman 
could  with  (lifHculty  ford  in  winter,  Itut  all  coininunicatioii  was  by  boat  in 
sunnner.  Then  the  water  fell  for  a  series  of  years,  until  in  iSdO  and  ISdl 
the  bar  was  again  dry  in  winter.  The  spring  of  ISll-J  was  iTiarked  \)y  an 
unusual  fall  of  rain  and  snow,  wherebv  the  streaius  were  greatly  Hooded 
and  the  lake  siu'face  was  raised  several  feet.  In  subsequent  yeai-s  tlie  rise 
continued,  until  in  1.SG5  the  ford  became  impassable.     According  to  Mr. 


TKADITIONAL  HISTOKY  OF  GKEAT  8ALT  LAKE.  241 

Hiller,  tlie  rise  was  somewhat  rapid  until  1868,  from  which  date  until  the 
establishment  of  the  gauges,  there  occurred  only  minor  fluctuations. 

Since  these  paragraphs  were  written  the  publication  of  Fremont's 
"Memoirs  of  My  Life"  has  afforded  a  still  earlier  observation.  On  the  liith 
of  August  1845  he  rode  across  the  shallows  to  Antelope  Island,  the  water 
nowhere  reaching  above  the  saddle  girths.' 

For  the  purpose  of  connecting  the  traditional  history  as  derived  from 
the  ford  with  the  systematic  record  afterward  inaugurated,  I  visited  the  bar 
in  company  with  Mr.  Miller  on  the  19tli  of  October  1877,  and  made  careful 
soundings.  The  features  of  the  ford  had  been  minutely  described,  and  there 
was  no  uncertainty  as  to  the  identification  of  the  locality.  We  found  D  feet 
of  water  on  the  sand  flat,  and  9  feet  6  inches  in  the  little  channel  at  its  eda-e. 
The  examination  was  completed  at  11  a.  m.;  at  5  p.  m.  the  water  stood  at 
10  inches  on  the  Black  Rock  gauge. 

The  Antelope  Island  bar  thus  affords  a  tolerably  complete  record  from 
1845  to  1865,  but  fails  to  give  any  later  details.  It  hap2)ens,  however,  that 
the  hiatus  is  filled  at  another  locality.  Stansbury  Island  is  joined  to  the 
mainland  by  a  similar  bar,  which  was  entirely  above  water  at  the  time  of 
Capt.  Stansbury's  survey,  and  so  conthiued  for  many  years.  In  1866,  the 
year  following  that  in  which  the  Antelope  bar  became  unfordable,  the  water 
for  the  first  time  covered  the  Stansbury  bar,  and  its  subsequent  advance 
and  recession  have  so  affected  the  pursuits  of  the  citizens  of  Grantsville 
wilt)  used  the  island  for  a  winter  herd  ground,  that  it  will  not  be  difficult 
to  obtain  a  fidl  record  by  compiling  their  incidental  observations.  While 
making  the  inipiiry  I  had  no  opportunity  to  visit  that  town,  but  elicited  the 
following  facts  by  correspondence.  Since  the  first  flooding  of  the  Ijar  the 
dej)th  of  water  has  never  been  less  than  a  foot,  and  it  lias  never  been  so 
great  as  to  prevent  fording  in  winter.  But  in  the  summers  of  1872,  1873 
and  1874,  during  the  flood  stage  of  the  annual  tide,  there  was  no  access 
except  by  boat,  and  in  those  years  the  lake  level  attained  its  greatest  lieight. 
In  the  spi'ing  of  1869  the  depth  was  4 J  feet,  and  in  the  autumn  of  1877,  2 J 
feet. 

'Vol.  1,  p.  431. 
MON  I 16 


242  LAKE  BONNEVILLE. 

The  last  item  shows  tliat  the  Stansbury  bar  is  7  feet  higher  than  the 
Antelope,  and  serves  to  connect  the  two  series  of  observations. 

Further  inquiries  may  render  the  record  more  complete  and  exact,  but 
as  it  now  stands  all  the  general  features  of  the  fluctuations  are  indicated  as 
far  back  as  1845.  Beyond  that  time  there  is  no  tradition,  but  there  is  a 
single  item  of  circumstantial  evidence  worthy  of  mention.  All  about  the 
lake  shore  there  is  a  storai  line  marking  the  extreme  advance  of  the  water 
during  gales  in  the  summers  of  1872,  1873  and  1874.  It  is  indicafed  by 
driftwood  and  other  shore  debris  and  is  especially  distingui.shed  by  the  fact 
that  it  marks  a  change  in  vegetation.  In  some  places  vegetation  ceases  at 
this  line,  but  usually  there  is  a  straggling  growth  of  herbaceous  plants  able 
to  live  on  a  saline  soil.  Above  the  line,  on  all  the  steeper  slopes  not  sub- 
jected to  cultivation,  the  sage  and  other  bushes  flourish,  but  below  the  line 
they  are  represented  only  by  their  dead  stumps.  The  height  of  this  storm 
line  above  the  contemporaneous  still-water  surface  varies  with  the  locality, 
being  much  greater  on  a  shelving  coast,  over  which  the  water  is  forced  to  a 
considerable  distance  by  the  winds,  and  especially  small  upon  the  islands. 
On  the  east  side  of  Antelope  Island  it  was  found  by  measurement  to  be 
three  feet  above  the  summer  stage  of  the  lake  in  1877,  or  about  one  foot 
above  the  winter  stage  in  1873. 

A  lower  storm  line  was  observed  by  Stansbury  in  18.50,  and  has  been 
described  to  me  by  a  number  of  citizens  of  Utah  who  were  acquainted  with 
it  at  that  time  and  subsequently.  The  lake  was  then  at  its  lowest  observed 
stage;  and  the  storm  line  was  so  little  above  it  that  it  was  submerged  soon 
after  the  rise  of  the  lake  began.  Like  the  line  now  visible,  it  was  marked 
by  di-iftwood,  and  a  growth  of  bushes,  including  the  sage,  extended  down 
to  it;  but  below  it  no  stumps  were  seen. 

The  relations  in  time  and  space  of  these  two  storm  lines  contribute  a 
page  to  the  history  of  the  lake.  The  fact  that  the  belt  of  land  between 
them  supported  sage  bushes  shows  that  previous  to  its  present  submergence 
it  had  been  dry  for  many  years.  Lands  washed  by  the  brine  of  the  lake 
become  saturated  with  salt  to  such  an  extent  that  even  salt-loving  plants 
can  not  live  upon  them;  and  it  is  a  familiar  fact  that  the  sage  never  grows 
in  Utah  upon  soil  so  saline  as  to  be  unfavorable  for  grain.     The  rains  of 


SECULAK  OUEVE  OF  GEEAT  SALT  LAKE. 


243 


many  years,  and  perhaps  even  of  centuries,  would  be  needed  to  cleanse 
land  abandoned  by  the  lake  so  that  it  could  sustain  the  salt-hating  bushes; 
and  we  cannot  avoid  the  conclusion  that  the  ancient  storm  line  had  been 
for  a  long  period  the  limit  of  the  fluctuations  of  the  lake  surface. 


1 

1 

^ 

7j 

^ 

OS. 

_ 

.' 

\ 

^ .   .__ 

/ 

-^^ 

'' 

/ 

^-^ 

■\ 

"■-----'' 

\ 

.-'-'' 

\ 

.inr 

Fig.  33.— Xon-Pi  rioilio  Ri.so  and  Fall  of  Great  Salt  Lake. 

A.  I.  7!.  =  Aiitiloim  Island  Bar.  S.  I.  B.  i^Staiisbuiy  Ishind  Car.  O.  .S".  =  Old  Storm  line.  JV.  .S.  =  New  Storm 
line.  The  borizootal  scale  represtuta  time.  The  vertical  scale  of  feet  is  referred  to  the  zero  of  the  Lake  Shore  Gauge  as  a 
datum. 

The  curve  in  Fig.  33  embodies  the  results  of  direct  observation  and  of 
traditional  evidence  as  well  as  the  inference  from  the  phenomena  of  the 
ancient  shore-hne.  It  is  th-awn  as  a  full  line  where  based  upon  definite 
information,  and  as  a  broken  line  where  the  data  are  less  precise.  That  to 
the  left  of  the  ordinate  representing  1845  is  intended  to  express  merely  the 
postulate  that  there  were  then,  as  afterward,  oscillations,  and  the  conclusion 
that  those  oscillations  did  not  exceed  the  level  of  the  ancient  storm-line. 
The  annual  oscillation  is  omitted;  the  non-periodic  only  is  represented. 

The  principal  facts  illustrated  by  this  curve  are,  that  during  the  historic 
period  in  Utah  the  lake  has  twice  risen  and  twice  fallen,  the  second  fall  being 
now  in  progress;  that  the  second  rise  was  carried  five  feet  above  a  line  which 
had  not  been  submerged  for  several  decades;  and  that  the  total  observed 
range  of  fluctuation  is  about  eleven  feet. 

Changes  in  arca.-Tlie  inclination  of  the  shores  is  in  many  directions  so  grad- 
ual that  this  oscillation  of  eleven  feet  has  been  accompanied  by  very  notable 
changes  in  the  extent  of  the  water  surface.  Fortunately,  the  two  maps  of 
the  lake  that  have  been  published  are  based  upon  surveys  made  at  such 
times  as  to  illustrate  this  change.  Stansbury  perfonned  his  field  work  in  the 
years  1849  and  1850,  when  the  lake  was  at  its  lowest  observed  level,  and 
the  topographers  of  the  Fortieth  Parallel  Survey  delineated  the  lake  margin 
in  1869,  when  the  water  was  mthin  a  few  inches  of  its  highest  stage.     PI. 


244  LAKE  BONNEVILLE, 

XXXIII  is  compiled  from  the  two  maps  conjointly,  so  as  to  exhibit  tlie 
position  and  extent  of  the  belt  of  land  submerged  by  the  rise  of  the  lake. 
Upon  the  Stansbur}'  map  the  water  surface  has  an  area  of  1750  miles;  up(ni 
the  King,  or  Fortieth  Parallel  ma]),  an  area  of  2170  miles,  the  increment 
being  24  per  cent,  of  the  smaller  area. 

The  ability  of  the  lake  to  dilate  rapidly  the  water  surface  exposed  to 
evaporation  must  ordinarily  prevent  any  great  fluctuation  in  its  height. 
The  effect  of  each  temporary  increment  or  decrement  to  either  water  sup})ly 
or  rate  of  evaporation  is  by  this  means  quickly  obliterated,  and  cumulative 
results  are  prevented.  The  lake  level  must  be  conceived  to  fluctuate  nor- 
mally within  narrow  limits,  and  the  last  high  stage,  in  which  the  water  was 
not  merely  carried  above  the  old  storm  line,  but  maintained  at  a  greater 
altitude  for  a  period  of  eight  or  nine  years,  may  be  assumed  to  indicate 
some  powerful  and  unusual  cause. 

Causes  ofchangc-Tlie  fact  tluit  tlic  exceptional  lake  maximum  has  occurred 
during  the  occupation  of  the  region  by  the  white  man  suggests  that  it  may 
have  been  occasioned  in  some  way  by  human  agency;  otherwise  its  cause 
is  natural,  and  is  almost  of  necessity  climatic.  Let  us  first  consider  the  pos- 
sible climatic  causes.  The  height  of  the  lake  is  stationary  only  when  the 
gain  from  inflow  and  from  rainfall  on  the  water  surface  is  precisely  balanced 
by  the  loss  from  evaporation.  Whenever  in  any  year  the  total  access  of 
water  exceeds  the  evaporation,  the  surface  rises;  when  the  evaporation  ex- 
ceeds, the  surface  falls.  The  elements  of  climate  to  be  considered  are  there- 
fore those  which  affect  the  water  supply  and  the  evai)oration.  The  rate  of 
evaporation  is  a  function  of  the  local  temperature  and  humiditv  of  the  air 
and  of  the  velocity  of  the  wind.  The  water  supply  depends  ])rimarilv  on 
the  rainfall  and  secondarily  on  the  I'ate  of  evaporation,  since  a  jxHtion  of 
the  water  falling  on  the  land  is  evaporated,  and  it  is  only  the  unevaporated 
part  which  finds  its  Avay  to  the  lake.  Other  things  being  ecjual,  the  lake 
surface  should  rise  during  those  years  in  which  the  precipitation  in  rain  and 
snow  is  great,  the  temperature  low,  the  relative  humidity  liigh,  or  the  wind 
velocity  small. 

Our  climatic  record  in  the  Cordilleras  is  imperfect,  but  such  as  it  is,  it 
extends  back  nearly  as  far  as  the  record  of  lake  oscillation.     The  account 


U  S. GEOLOGICAL    SUPA'-S-: 


LAKE  B0NNE'.1LLE     PL- XXXHI 


I  i  11  1    r  ± 


Julius  BiCTi  &  Co  Lith 


COMPARATI\'E    MAP  OF 

GREAT    SALT  LAKE  ,  UTAH 

COMPILKn  TO   SHOW 

ITS  INCREASE  OF  AREA. 

ThtTopoqraphy  and  lattr  sfiorc-line  fwe  taken  from  the  Sui-veyot'(2arfn^efang, 
U.a. Geologist;  the  earlier  shorerUne.  from  the  Survey  of(hptMow(wd  StansburyUSA. 


WHY  DOES  THE  LAKE  RISE  AND  FALL?  245 

it  affords  of  the  wind  velocity  and  tlie  relative  humidity  is  not  sufficiently 
definite  to  be  of  value  in  this  connection;  but  the  records  of  rainfall  and 
temperature  may  profitably  be  compared.  For  this  ])ui-pose  I  have  availed 
myself  of  the  statistics  gathered  by  the  Smithsonian  Institution  and  discussed 
by  Mr.  Charles  A.  Schott  in  his  papers  on  the  precipitation  and  atmos])heric 
temperature  of  the  United  States,  and  those  gathered  and  published  by  the 
U.  S.  Signal  Corps. 

Aqueous  precipitation  is  so  capricious  in  its  distril)ution  that  the  record 
kept  at  a  single  station  affords  no  valuable  indication  of  secular  changes. 
It  is  only  by  the  combination  of  a  system  of  observations  made  at  a  gi'oup 
of  stations,  that  any  trustworthy  indication  can  ])e  obtained.  For  the  present 
purpose  the  stations  of  the  Great  Basin  and  of  the  adjacent  portions  of  the 
Pacific  Coast  have  been  used,  choice  being  restricted  t<i  those  at  which 
records  have  been  kept  for  terms  of  years.  These  are:  Astoria  and  Port- 
land, Oregon;  Fort  Point,  Sacramento,  San  Fi-ancisco  and  San  Diego,  Cal- 
ifornia; Boise  City  and  Fort  Boisti,  Idaho;  Salt  Lake  City  and  Camp 
Douglas,  Utah.  In  the  reduction  of  the  observations  the  precipitation  for 
each  year  and  station  has  been  divided  by  the  mean  annual  precipitation 
for  that  station,  and  the  several  quotients  have  been  arranged  under  their 
appropriate  years.  The  mean  of  all  the  quotients  for  each  year  has  then 
been  found,  and  these  means  have  been  assumed  to  express  the  relative 
precipitation  for  the  several  years  in  the  indicated  districts.  The  curve 
representing  these  means  is  reproduced  in  No.  1  of  PI.  XXXIV. 

A  brief  consideration  will  show  that  this  curve  is  not  directly  compara- 
ble with  the  curve  of  lake  oscillation,  III.  Assuming  for  the  moment  that 
the  oscillations  of  the  lake  are  determined  purely  by  variations  of  precipita- 
tion, then  each  year  of  excessive  precipitation  should  correspond  to  a  rise 
of  the  lake,  and  each  year  of  small  precipitation  to  a  fall.  A  maximum  of 
lake  level  would  occin-  at  the  end  of  a  series  of  years  of  great  rainfall,  but 
would  not,  except  by  accident,  correspond  in  time  with  a  year  of  maximum 
rainfall.  If  the  area  of  the  lake  and  the  rate  of  evaporation  were  constant, 
the  height  of  the  lake  level  at  any  time  could  be  determined  by  the  summa- 
tion of  all  the  precedent  precipitation  factors  up  to  that  time ;  liut  the  fact 
that  the  lake  expands  as  it  rises  causes  the  annual  loss  by  evaporation  to  be 


246  LAKE  BONNEVILLE. 

a  function  of  the  lake's  lieight.  Tlie  exceptionally  great  rainfall  of  an  indi- 
vidual year,  by  increasing  the  area  of  the  lake,  initiates  an  excess  of  evapo- 
ration which  eventually  eliminates  its  influence  from  the  curve  of  lake 
oscillation;  the  exceptionally  small  rainfall  of  an  individual  year,  by  dimin- 
ishing the  area  of  the  lake,  initiates  a  defect  of  evaporation  which  likewise 
eventually  eliminates  its  influence  from  the  curve  of  lake  oscillation.  The 
height  of  the  lake  at  any  time,  as  dependent  on  precipitation,  is  therefore  to 
be  derived  by  such  an  integration  of  the  precipitation  of  antecedent  years 
as  will  give  the  greatest  weight  to  the  years  just  passed  and  a  progressively 
smaller  weight  to  those  more  remote.  An  integration  of  this  sort  has  been 
made,  and  is  expressed  in  the  curve  marked  II.  It  was  arbitrarily  assumed 
that  the  influence  upon  the  lake  level  of  the  precipitation  of  a  given  year 
diminished  in  arithmetic  ratio  so  as  to  disappear  in  ten  years,  and  the  inte- 
gration was  based  on  this  assumption.  For  example,  the  factor  for  1870 
was  multiplied  by  ten,  that  for  18G9  by  nine,  that  for  18G8  by  eight,  etc., 
the  factor  for  18G1  being  the  last  included  and  being  multiplied  by  unity. 
The  sum  of  these  several  products  was  divided  by  the  sum  of  the  multipliers, 
55,  and  the  quotient  was  assumed  to  represent  the  integrated  precipitation 
factor  at  the  end  of  the  year  1870. 

The  temperature  was  treated  in  a  sunilar  manner.  Prior  to  the  insti- 
tution of  the  meteorologic  observations  of  the  Signal  Corps,  temperature 
was  observed  at  a  number  of  military  posts  and  a  few  cities,  and  the  records 
have  been  compiled  and  discussed  by  Mr.  Schott.  These  observations  have 
doubtless  been  continued  at  most  points  up  to  the  present  time,  but  they 
are  less  accessible  than  those  of  the  Signal  Service,  and  the  latter  have  been 
employed  for  the  period  from  1872  to  1883.  The  Signal  Service  stations 
in  the  region  already  indicated  include  Portland,  Ore.,  and  San  Francisco, 
and  San  Diego,  Cal.,  occupied  for  the  entire  period;  and  Umatilla,  Ore., 
Visalia,  Cal.,  Boise  City,  Idaho,  Salt  Lake  City,  Utah,  Pioche,  Nev.,  and 
Prescott,  Ariz.,  occupied  for  terms  varying  from  five  to  eight  years.  For 
each  of  these  stations  the  mean  of  the  annual  means  of  temperature  was 
subtracted  from  each  of  the  annual  means,  and  the  residuals  were  arranged 
in  columns  according  to  years.  The  mean  of  the  residuals  for  each  year 
was  then  deduced,  and  the  successive  mean  residuals  were  plotted  in  a  curve. 


U  S. GEOLOGICAL    SURVEY 


LAKE  BONNEVILLE     PL.  XXXIV 


50 


'60 


'70 


'80 


II               II 

II        III                          -.-..-  .... 

1   4 

K 

IT 

12          JL                               ^5 

t 

ft     ^           Ljrr^ 

t                 A                 -/5              1 

''       H^^^                  4     ^          -i 

15:5,      Ai^v  ^^     /_     V 

M  y  \-    ^i    i-A4 

^V    ^         ^^         ^^. 

« ^        t^^        y  i 

2lt                  V              ^     \ 

v--^                          W      TJ 

6 

J^^^ 

7      Y 

A     A^^y^^ 

t      ^^^r^-.         >^      n 

^^       ^^                             -JU 

-^                          V   A   S^^ 

■^I^         A               /X 

4                            Ay'^      V 

Kt            V-            ^-5 

I                            ^^            A 

At          ^        7       ^ 

'-t-           K     A4^  ^ 

X3I 

^'»».^'^""*^\^ 

+  6    ft 

/                   ^/^N 

>                               S 

+   4 

/                                   \          Itt 

/                                       > 

+   2                                                                                  2 

^^. 

^^1                                      ^ 

^. 

0                        /      ^\,                           / 

/                      \                    / 

-  2        ^                         3               ^ 

■^                                S^     ^ 

y^r-A. 

_j    ^^               "^ 

-.^  X     i^ 

^                         t 

z     ^==^ 

T 

y^'           \ 

V 

r-"                                                                          "^^ 

>, 

-u-"^ 

\ 

^^^ 

i                 + 

-—^    \,' 

+   2-         \ 

-t-r         ^v      S 

I^                       A 

\^     UA 

t^              ^V^     ^^             ^ 

0  it        V      V^ 

•                                                               \                M rf                                                                         \ 

\                    h 

A   i                    ^  / 

-1°                               V^^     S-^ 

^  \4  ^              C  V 

^^  \r  ^ 

-t-tt                  ^ 

-  Z' 

T                    ^ 

1 

L.l  1               III 

Julius  Bien  *  Lo.hdi 


CLIMATE    CURVES 


LAKE  CURVES  AND  CLIMATE  CURVES.  247 

This  curve  was  found  to  be  almost  identical  with  that  derived  from  the  San 
Francisco  observations  alone  and  to  be  closely  simulated  by  the  curves  of 
the  other  individual  stations.  It  was  therefore  deemed  legitimate  to  employ 
the  San  Francisco  curve  as  representative  of  the  district  for  the  period 
antecedent  to  the  institution  of  the  Signal  Service  observations. 

The  San  Francisco  observations,  however,  were  not  employed  alone. 
Mr.  Schott  has  combined  with  them  data  from  Alcatraz  Island,  Angel  Island, 
Fort  Point  and  Presidio,  all  of  which  stations  were  in  the  immediate  vicinity. 
His  results  are  published  in  the  form  of  mean  annual  temperatures,  and 
these  have  been  prepared  for  the  present  purpose  by  subtracting  from  each 
the  mean  of  the  series.  The  residuals  thus  obtained  and  the  residuals  de- 
rived from  the  Signal  Service  observations  are  plotted  in  curve  V  of  PI. 
XXXIV.  This  curve  may  be  considered  to  represent,  with  a  fair  degree 
of  approximation,  the  non-periodic  oscillations  of  temperature  within  the 
indicated  period  in  the  district  of  the  Great  Basin  and  Pacific  Coast. 

Here,  too,  it  is  evident  that  a  direct  comparison  with  the  curve  of  lake 
oscillation  should  not  be  made;  whatever  the  influence  of  temperature  upon 
the  volume  of  the  lake,  whether  through  rainfall  or  evaporation,  it  would 
be  semi-cumulative.  The  temperature  determinations  have  therefore  been 
submitted  to  the  same  process  of  special  integration  as  the  precipitation 
determinations;  it  was  again  assumed  that  the  influence  of  each  year's 
temperatin-e  would  diminish  in  arithmetic  ratio  so  as  to  disappear  in  ten 
years.  The  deduced  curve,  IV,  is  far  more  regular  than  that  derived  from 
precipitation,  and  presumably  represents  the  slow  secular  oscillation. 

In  comparing  the  integrated  temperature  curve  with  the  curve  of  lake 
oscillation  the  question  arises  whether  the  maxima  of  the  former  should  be 
compared  with  the  maxima  or  the  minima  of  the  latter.  If  temperature 
affects  the  lake  chiefly  through  rate  of  evaporation,  the  maxima  of  one  curve 
should  coincide  with  the  minima  of  the  other.  If  its  chief  influence  is  ex- 
erted through  precipitation,  the  correspondence  should  probably  be  found 
in  the  same  way;  but  about  this  there  is  diftereuce  of  opinion.  Fortunately, 
it  is  unnecessary  to  discuss  the  subject  in  this  connection,  for  whether  the 
comparison  be  made  directly  or  by  inversion,  it  is  equally  evident  that  the 
curves  are  inharmonious. 


248  LAKE  BONNEVILLE. 

Tlie  integrated  precipitation,  curve  IT,  resembles  the  curve  of  oscilla- 
tion in  several  })articulars.  Its  maxinmm  from  1852  to  1855  is  comparable 
with  the  lake  maximmn  in  1855  and  is^fi.  Its  minimnm  from  1858  to  18G0 
is  comparable  with  the  lake  mininmm  in  1860  and  1861;  and  dui-ing  the 
great  maxinunn  of  the  lake  from  1867  to  187!)  the  precipitation  curve  is 
for  the  ]nost  part  above  its  mean  line.  The  only  great  disparity  occurs  in 
the  years  1S(;8  to  1865,  when  the  precipitation  curve  shows  a  minimum 
unrepresented  in  the  curve  of  lake  oscillation.  The  precipitation  curve  is 
therefore  on  the  whole  similar,  and  indeed  its  correspondence  is  quite  as 
close  as  could  be  expected  by  one  who  realizes  how  imperfectly  the  average 
precipitation  of  a  region  is  rejjresented  by  the  observed  precipitation  at 
a  small  number  of  stations.  There  is,  therefore,  some  su])port  for  the 
hypothesis  entertained  by  many  ])ersous  that  the  exceptional  rise  of  Great 
Salt  Lake  which  culminated  in  1873  was  due  to  au  increase  of  precip- 
itation.^ 

Turning  noAv  to  the  consideration  of  the  influences  exerted  upon  the 
lake  by  man,  we  find  them  separable  into  two  classes;  first,  those  which  cause 
a  greater  proportion  of  the  precipitation  falling  on  the  Innd  to  be  gathered 
by  the  streams  and  carried  to  the  lake;  second,  those  which  cause  a  smaller 
pro]iortion  of  the  precipitation  to  reach  the  lake.  The  supposed  influence 
of  deforesting  on  the  rainfall  itself  need  not  be  discussed,  because  in  this 
region  no  considerable  body  of  forest  has  been  destroyed. 

The  chief  influence  of  man  in  increasinfj  the  inflow  of  the  lake  is  through 
the  grazing  industry.  In  their  virgin  condition  many  of  the  lowland  vallej-s 
and  all  the  upland  or  mountain  valleys  were  covered  by  grass  and  other 
herbaceous  vegetation.  These  have  been  eaten  off"  Ijy  the  herds  of  the  white 
man,  and  in  their  place  has  sprung  up  a  sparse  gi'owth  of  low  bushes  between 
which  the  ground  is  bare.  From  this  bare  svirface  it  is  believed  that  the 
water  falling  as  rain  or  freed  by  the  melting  of  snow,  runs  off  more  readily 
than  from  the  original  grassy  surface,  so  that  a  smaller  share  of  it  is  evap- 
orated in  situ  and  a  larger  share  flows  through  the  water  courses  to  the 
lake.     This  change  has  affected  a  large  total  area;  and  if  its  influence  ujjon 

'  The  observational  data  discussed  close  with  the  year  1883.  As  the  niauusoript  goes  to  press 
they  are  available  to  1889.  The  later  data  have  not  been  systematically  treated,  but  their  inspection 
shows  that  the  general  conclusion  is  sustained  by  them. 


MAN'S  INFLUENCE  ON  GREAT  SALT  LAKE.  249 

water  supply  is  here  coiTOctly  interpretecl,  it  is  a  factor  of  importance. 
Another  tactor  of  tlie  same  tendency  is  the  draining-  of  marshes  and  beaver 
ponds.  IMany  of  the  small  streams  of  the  basin  were  clogged  by  beaver 
dams,  and  the  courses  of  some  of  these  have  been  opened  by  the  white  man 
for  the  purpose  of  increasino-  the  supply  of  water  for  irrigation.  The  in- 
creased su])ply  has  been  utilized  for  irrigation  during  a  portion  only  of  the 
year,  and  at  other  times  has  joined  the  streams  flowing  to  the  lake. 

Plowing  and  irrigation  have  the  contrary  effect.  Land  broken  up  for 
cultivation  is  tliei-eby  rendered  more  porous,  so  as  to  retain  a  larger  portion 
of  the  rain  falling  upon  it.  I'liis  i-etained  portion  is  chiefly  returned  to  the 
atmosphere  by  evaporation  and  is  tluis  lost  to  the  lake.  The  effect  of  irriga- 
tion is  precisely  similar.  The  water  diverted  from  the  streams  and  spread 
out  on  the  land  for  the  })urpose  oH  nourishing  crops  is  restored  to  the  atmos- 
l)here  by  evaporation  from  the  surface  of  the  soil  and  from  the  leaves  of 
plants.  In  1877  the  writer  estimated  that  the  inflow  of  Great  Salt  Lake 
was  diminished  six  per  cent  by  this  cause. 

With  the  exception  of  iri-igation,  it  is  impossible  to  give  quantitative 
expression  to  these  factors.  Those  which  tend  to  increase  the  lake  })robably 
culminated  fifteen  or  twenty  years  ago,  and  have  .since  remained  constant. 
Those  which  tend  to  diminish  the  lake  have  increased  continuously  for  the 
last  35  years.  The  time  is  probably  past  when  the  net  tendency  toward 
lake  increment  was  at  a  maximum,  but  it  is  not  entirely  clear  whether  the 
present  sum  of  human  agencies  tends  toward  lake  expansion  or  lake  con- 
traction. Li  any  case  the  consideration  of  the  qualitative  relation  of  the 
several  factors  suffices  to  sliow  that  a  curve  representative  of  the  influence 
of  hinnan  agencies  could  have  but  a  single  maximum,  and  could  not  corre- 
spond in  detail  with  the  determined  curve  of  oscillation. 

Ten  years  ago  I  discussed  at  some  length  the  comparative  merits  of 
the  climatic  theory  and  the  theory  of  human  agencies,'  concluding  that 
neither  was  inconsistent  with  the  facts  and  that  the  truth  might  include 
both.  I  pointed  out  that  the  former  appealed  to  a  cause  that  may  be  ade- 
quate but  is  not  independently  known  to  exist,  while  the  latter  appealed  to 
causes  known  to  exist  but  quantitatively  undetei'mined.     Since  that  time 

'  Lands  of  the  Arid  Region,  pp.  68-77. 


250  LAKE  BONNEVILLE. 

the  publication  of  the  second  edition  of  Mr.  Schott's  discussion  of  i-ainfall 
and  the  progress  of  the  work  of  the  U.  S.  Signal  Corps  have  rendered  it 
j^ossible  to  construct  the  most  iinportant  fom])arative  climatic  curves,  and 
the  subject  is  here  resumed  for  the  purpose  of  exhibiting  the  relation  of 
these  curves  to  the  curve  of  oscillation.  The  coiTcsjiondence  of  the  inte- 
grated precipitation  curve  to  the  curve  of  lake  oscillation  is  siifficientlv  close 
to  indicate  a  causal  relation,  especially  in  view  of  the  fact  that  rainfall  is  the 
climatic  factor  to  which  hypothesis  most  naturally  appeals. 

In  the  present  as])ect  f)f  the  problem,  precipitation  seems  entitled  to 
rank  as  the  dominant  factor,  the  results  of  its  variation  being  only  slightly 
modified  by  the  variations  of  temperature  and  the  changes  introduced  by 
gi-azing  and  agriculture. 

Future  changes.-Thosc  humau  ageucles  which  tend  to  increase  the  water 
supplv  of  the  lake,  namely,  grazing  and  draining,  have  acquired  a  status 
that  is  practically  permanent,  but  those  which  tend  to  diminish  the  supplv, 
namely,  plowing  and  irrigation,  have  not  yet  ceased  to  increase.  In  1877, 
when  the  consumption  of  water  by  irrigation  w.as  estimated  at  six  per  cent,  of 
the  inflow  of  the  lake,  the  intervention  of  the  irrigator  was  restricted  to  the 
minor  streams  of  the  basin.  The  main  bodies  of  the  Bear  and  of  the  Jordan, 
the  largest  of  all  the  streams,  flowed  unimpeded  to  the  lake.  Since  that 
time,  the  diversion  of  the  water  of  the  Jordan  has  been  undertaken  on  a 
large  scale ;  and  the  time  can  not  be  distant  when  its  entire  volume  will  be 
utilized.  The  Bear  River  presents  greater  engineering  difficulties,  and  has 
not  yet  been  brought  under  control;  but  sooner  or  later  a  large  district  will 
be  redeemed  by  means  of  its  water,  and  the  lake  will  be  correspondingly 
deprived  of  tribute.  Human  agency  is  thus  destined  to  play  an  iniportant 
part  in  the  detemaination  of  the  future  history  of  the  lake.  The  next  ten 
years  will  witness  its  shrinkage,  for  lack  of  affluent  water,  to  a  size  smaller 
than  has  before  been  observed.  It  is  not  to  be  expected  that  it  will  ever 
share  the  fate  of  Sevier  Lake,  because  the  conservation  of  all  the  stream 
water  for  irrigation  is  not  economically  practicable,  but  it  will  })i"obably  be 
so  reduced  in  voliune  as  to  precipitate  a  portion  of  its  salt. 

The  final  system  of  irrigation  will  include  the  storage  in  artificial 
reservoirs  of  the  flood  water  of  all  the  minor  streams,  and  will  cause  the  lake 


FUTURE  SHRINKING  PROPHESIED.  251 

to  be  deprived  of  all  inflow  except  from  saline  creeks  and  from  the  unused 
share  of  Bear  River,  l)ut  this  system  is  not  likely  to  be  established  by  the 
present  generation.  The  expansion  of  the  methods  now  in  vogue  to  a  limit 
dependent  on  the  extent  of  tlie  readily  available  arable  land,  together  with 
the  construction  of  reservoirs  on  the  most  available  sites,  will  employ  about 
two-thirds  of  the  water  supplv,  and  will  proportionately  reduce  the  area  of 
the  lake. 

One  effect  of  si;ch  a  contraction  of  the  lake  will  be  to  simplifv  its  out- 
line. Antelope,  Stansbury,  Carrington,  Hat,  and  Dolphin  islands  will  he 
permanently  united  to  the  land.  Bear  River  Bay  will  be  drained  nearly  to 
the  southern  extremity  of  Promontory,  and  the  bay  east  of  Antelope  Island 
will  be  drained  nearly  to  the  northern  end  of  that  island.  The  Jordan,  the 
Weber,  and  the  Bear  will  iniite  their  deltas  in  the  vicinity  of  Fremont 
Island,  and  will  eventually  fill  up  all  of  the  sound  east  of  that  island, 
reducing  the  lake  to  a  linear  body  lying  east  of  Stansbury  Island  and  the 
Promontory.  With  a  lowering  of  the  lake  siu-face  the  projection  of  deltas 
^will  be  a  rapid  process.  During  the  recent  high  stage  of  the  lake  the  chan- 
nels of  the  three  principal  rivers  have  been  converted,  in  their  lower  por- 
tions, into  estuaries  whose  sluggish  current  has  permitted  the  accumulation 
of  silt.  The  volume  of  this  silt  has  been  at  the  same  time  increased  by  the 
culti^'ation  of  the  soil,  an  industry  which  always  augments  the  detrital  loads 
of  the  streams.  The  lowering  of  base-level  incident  to  the  falling  of.  the 
lake  surface  will  cause  the  streams  to  erode  this  detritus  and  transport  it  to 
the  shore  of  the  lake. 

Saline  Contents-Auother  cffcct  will  bc  the  concentration  of  the  brine.  The 
lake  is  so  shallow  that  its  volume  is  greatly  affected  by  small  changes  of 
level,  and  since  the  total  amount  of  contained  salts  undergoes  no  appre- 
ciable change,  the  strength  of  the  solution  is  affected.  Variations  of  salinity 
have  been  observed  by  persons  engaged  in  the  manufacture  of  salt  from  the 
brine,  and  quantitative  expression  lias  been  given  to  the  same  facts  by  the 
analyses  made  from  samples  gathered  at  different  dates.  With  the  lake  at 
its  lowest  observed  stage,  1850,  Stansbury  collected  a  sample  of  the  brine 
containing  22.4  per  cent,  of  solid  matter.  From  a  sample  gathered  in  1873, 
when  the  lake  was  at  its  highest  stage,  Bassett  obtained  13.7  per  cent,  of 


252  LAKE  BONNEVILLE. 

solid  matter.  At  an  intemiediate  stage  King-  collected  in  1869  a  sample 
containing  14.8  per  cent,  and  Talmage  in  1885  and  1889  obtained  samples 
yielding  1(1.7  and  lit.G  per  cent.  It  would  appear  from  a  comparison  of  the 
extreme  results  that  with  a  rise  of  the  lake  surface  of  10^  feet  the  salinity 
was  decreased  by  39  per  cent,  of  its  amount;  and,  assuming  that  the  quan- 
tity of  saline  matter  in  solution  remained  unchanged,  the  volume  of  water 
in  the  lake  was  at  the  same  time  increased  73  per  cent. 

While  these  results  are  approximately  true,  they  should  not  pass  with- 
out (pialification.  Careful  comparisons  of  the  several  determinations  of 
salinity  ^\\t\\  tlie  several  determinations  of  density  and  with  the  correspond- 
ing determinations  of  height  of  water  surface,  reveal  numerous  discrepancies. 
The  comparison  of  salinities  with  densities  shows  that  there  are  errors  in 
determinations  of  salinities  or  densities.  Discrepancies  between  determined 
salinities  or  densities  on  the  one  hand,  and  heights  of  water  surface  on  the 
other,  suggest  several  sources  of  error.  No  collector  of  water  samples  has 
placed  on  record  the  spot  where  the  collection  was  made;  one  may  have 
stopped  near  the  mouth  of  a  stream  and  obtained  too  low  a  salinity;  another 
may  have  visited  a  lagoon  of  the  shore  with  abnormally  high  salinity. 
Stansbury  and  King  neglected  to  record  the  dates  of  sampling;  and  of 
the  five  samples  analyzed  three  were  collected  before  the  establishment  of 
gauges;  there  is  thus  some  uncertainty  in  determinations  of  the  height  of 
the  lake  when  its  brine  was  sampled. 

The  accompanying  analyses  embody  all  our  knowledge  of  the  nature 
of  the  brine  and  they  accord  so  poorly  with  one  another  that  they  wai-rant 
our  speaking  with  confidence  oidy  of  the  most  striking  characteristics.  The 
principal  base  is  sodium,  and  this  exists  chiefly  in  the  form  of  chloride,  but 
also  as  sulphate ;  next  in  rank  is  potassium,  and  then  follow  magnesium  and 
calcium.  Despite  the  fact  that  calcium  carbonate  is  precipitated  on  the  shore 
in  the  form  of  an  oolitic  sand,  none  of  the  analysts  have  succeeded  in  iinding 
it  in  the  brine;  and  it  is  probable  that  the  weighable  calcium  found  in  two 
of  the  samples  exists  in  the  form  of  sulphate.  The  theoretic  combination 
of  acids  and  bases  given  in  the  lower  division  of  the  table  is  in  the  main 
tentative  only;  but  the  readiness  with  which  sodium  sulphate  is  ol)tained 
from  the  brine  Avarrants  the  belief  that  it  is  one  of  the  actual  constituents. 


THE  SALT  LAKE  BRINE. 


253 


Wlien  in  winter  the  temperature  of  the  water  falls  below  20°  F.,  the  precipi- 
tation of  this  salt  begins,  and  it  sometimes  accumulates  in  such  quantity  as 
to  be  readily  gathered  from  the  bottom,  or  is  even  thrown  upon  the  shore 
by  the  waves. 

The  sodium  chloride  has  become  the  basis  of  a  large  industry,  being 
manufactured  for  table  and  dairj-  use  as  well  as  for  metallurgic  purposes. 
This  industry  has  so  expanded  since  the  close  of  my  work  in  Utah  that  a 
statement  of  its  condition  at  that  time  Avould  have  historical  value  only.  It 
is  re})orted  that  the  output  in  1886  was  23,000  tons;  in  1887,  40,000  tons;  in 
1888,  21,000  tons.  For  several  years  sodium  sulpliate  cast  on  the  shore  Ijy 
the  waves  in  winter  has  been  gathered,  and  its  utilization  for  the  production 
of  various  sodium  salts  of  commercial  importance  is  already  undertaken.^ 
The  quantity  of  sodium  chloride  contained  in  the  lake  is  about  400  millions 
tons;  of  sodium  sulphate,  30  millions  tons. 

Table  IX.  Anahjses  of  Wate>-  of  Great  Salt  Lake. 

I.  Sample  taken  id  1850;  analysis  by  L.  D.  Gale. 
II.  Suniple  taken  in  summer  of  1869;  analysis  by  O.  D.  Allen. 

III.  Sample  taken  in  Auj;u8t.  1873;  analysis  by  H.  liassett. 

IV.  Sample  taken  in  December,  t885;  analysis  by  J.  E.  Talmage. 
V.  Sample  taken  in  August,  1889 ;  analysis  by  J.  E.  Talmage. 


I. 

II. 

III. 

IV. 

V. 

Total  aolids  in  1000  parts  of  water. . . 

224.2 

1.170 

148.2 
[1.111] 

136.7 
1,102 

167.2 
1.122 

195.5 
1.157 

First  arrangement  ofreaults;  by  acids  and  bases. 


Parts 

in  1000  of  water. 

Per  cent,  of  total  sulids. 

I. 

11. 

III. 

lY. 

V. 

I. 

II. 

III. 

IV. 

V. 

124.5 
12.4 
85.3 

84.0 

9.9 

49.6 

2.4 

.2 

3.8 

Trace 

Trace 

73.6 
8.8 

38.3 

9.9 

.6 

3.0 

90.7 

13  1 

58.2 

1.9 

.4 
2.9 

110.5 

11.7 

6.5.3 

2.1 

.8 
5.1 

55.8 
6.0 

38.3 

.3 

50.0 
6.6 

33.1 

1.0 

.2 

2.5 

51.9 
6.6 

28.6 

7.4 

.4 

2.2 

54.3 
7.8 

34.8 

1.1 

.3 

1.7 

56.5 
6.0 

33.4 

1.1 

•  4 

2.6 

Sulphuric  acid  (SO4) . . . 

Trace 
.6 

Total 

222.8 

149.9 

134.2 

167.2 

195.5 

100.0 

100.0 

100.0 

100.0 

100.0 

'The  waters  of  Great  Salt  Lake.    By  James  E.  Talmage.    Scieuoe,  vol.  14,  1889,  pp.  444-446. 


254 


LAKE  BONNEVILLE. 


Second  arrangement  of  results  ;  hy  theoretic  cnmhinatiotis  of  acids  and  bases. 


Parts  in  1000  of  water. 

Per  cent,  of  total  solids. 

I. 

II. 

III. 

IV. 

V. 

I. 

II. 

III. 

IV. 

V. 

Sodium  chloride 

202.0 

118.6 

88.5 
18.9 
11.9 
10.9 

2.0 
2.0 

135.9 

l.'.7.4 

90.7 

79.1 

65.9 
14.1 
8.9 
8.1 

1.5 
1.5 

B1.3 

80.5 

Mafjuoaiuin  chloride  ... 
Sodium  sulphate 

2.5 
18.3 

14.9 

9.3 

5.3 

.9 

.9 

11..1. 

14.2 
4.3 
1.5 

20.1 
10.5 
4.7 
2.8 

1.1 
8.2 

9.9 

6.2 

3.6 

.6 

.6 

6.7 

8.5 

2.6 

.9 

10.3 
5.4 
2.4 
1.4 

Chlorine  (excea.s) 



222.8 

149.  9 

134.2 

167.2 

195.  S 

100.0 

100.0 

100.0 

100.0 

lOO.O 

Xote.  The  first  sample  of  water  was  collected  by  Stansbary,  and  its  analysis  is  reported  on  p.  419  of  the  "Expedition 
to  the  Gre.it  Salt  Lake."  The  second  was  collected  by  the  Fortieth  PariUel  Survey,  .nnd  is  rt-poi  ted  in  Systematic  Gtolojjy, 
vol.  I,  p.  .'">02,  and  Descriptive  Geology,  vol  2,  p.  433.  The  third  was  collected  by  Dr.  W.  Marcet  in  August,  l>^73,  and  is 
reported  in  the  Chemical  News  for  Nov.  7th,  1873  (vol.  28,  p.  2:tG)  by  n.  Cassett.  The  fourth  and  fifth  were  collected  by 
J.  E.  I'almage  in  December,  1885,  and  August,  1889,  and  :ire  rei)ortcd  in  Science,  vol.  H,  1889,  p.  445.  Gale  reported  the 
salt.s  as  hero  given  in  the  first  column  of  the  second  table.  Allen's  repoit  includes  two  forais,  the  salts  being  given  in 
one  and  the  alkalis  and  acids  in  the  other.  Allen's  figures,  a.s  printed,  aro  not  perfectly  consistent:  the  report  of  the 
combined  salts  baa  been  used  in  deriving  the  figures  here  published.  Basaett's  report  was  published  in  the  form  here  given 
in  the  third  column  of  the  first  taltle.  The  entire  error  of  analysis  is  computed  iu  chlorine  in  the  second  table,  columns 
II  and  III.  Talma,  e'a  reaulta  were  published  in  the  form  given  in  the  first  part  of  the  second  table.  Gale's  and  Tal- 
mage's  errors  of  analysis  do  not  appear.. 

Sources  of  Saline  Matter.-Tlie  sources  of  tliG  saliiie  material  may  be  considered 
in  two  classes;  the  first  including  the  rivers,  the  second  the  littoral  springs. 
The  Bear,  the  Welder,  the  Jordan  and  a  small  number  of  creeks  rise  in  up- 
lands above  the  horizon  of  the  Bonneville  shore  and  bring  to  the  lake  water 
Avhich  is  sensibly  fresh,  containing  only  minute  quantities  of  mineral  matter. 
A  cordon  of  springs  about  the  shore  of  the  lake  rise  through  the  Bonneville 
beds,  and  are  so  far  charged  with  salts  leached  from  the  sediments  as  to  be 
perceptibly  brackish.  With  these  should  be  classed  also  the  Malade  River, 
the  upjjer  course  of  which  is  fresh,  while  the  lower  is  rendered  brackish  by 
the  accession  of  saline  water  from  thermal  springs  rising  in  the  lied  of  the 
stream'  Avithin  the  Bonneville  area.  With  only  our  2)resent  knowledge  it  is 
iinjjossilile  to  say  whether  the  fresh  rivers  or  the  In-ackish  springs  furnish 
the  greater  saline  tribute  to  the  lake.  The  rivers  only  have  been  subjected 
to  chemical  examination. 

The  constitution  of  the  Jordan  water  was  determined  from  a  sample 
collected  in  Utah  Lake,  the  source  of  tlie  river,  and  this  determination  is 
taken  to  represent  about  one-third  of  the  inflow  of  the  lake.  Bear  Kiver 
was  sampled  at  Evanston,  where  the  stream  lias  proliably  two-thirds  of  its 


ACCUMULATION  PERIOD. 


255 


maximum  volume  Since  this  river  furnishes  alxnit  luilf  the  water  supply 
of  the  lake,  the  sample  is  taken  to  represent  one-third  of  that  suppl)-.  The 
two  analyses  exhibit  the  constitution  of  two-thirds  of  the  fresh-water  tribute 
of  the  lake,  and  it  will  l)e  assumed  that  their  mean  shows  the  character  of 
the  entire  fresh-water  tribute.  In  the  following-  table  this  mean  is  compared 
with  the  analysis  of  the  lake  water  as  reported  by  Allen: 

Table  X.  Accumulation  Periods  for  Suhslnncen  contained  in  the  hrine  of 
Great  Salt  Lake. 


Sabatance. 

Parts  in  1000. 

V. 
Accumu- 
lation 
Period. 

I. 

Bear  River 

Water. 

II. 

Utah  Lake 
Water. 

III. 

Meau  of 

I  and   II. 

IV. 
Great  Salt 
Lake  Water. 

Cblorine 

.0040 
.  0105 
.0082 

.  01'J4 
.1306 
.0178 
Trace 
.0558 
.0186 

.0086 
.  0703 
.0130 
Trace 
.0405 
.0155 

84.  00 

9.87 

49.05 

2.40 

.25 

3.77 

Trace 

Trace 

Tears. 
34,  200 
490 
13,  400 

18 
850 

Su'pbniic  acid  .. 
Sodium 

Calcium 

Magnesium 

.0432 
.0125 

Phoapbonis 



Rate  and  Period  of  Salt  Accumulation.-At     the    tlmC    wllCU    Allcu's    Sample    of    briuC 

was  collected  the  lake  had  a  mean  depth  of  about  19  feet.  The  annual 
inflow  to  the  lake  has  been  appi'oximately  estimated  as  sufficient  to  add  5^ 
feet  to  its  depth.^ 

The  lake  volume  is  therefore  equaled  by  the  inflow  in  three  and  a  half 
years,  and  in  that  period  the  saline  strength  of  the  lake  is  increased  by  an 
amount  equal  to  the  saline  strength  of  the  inflow.  Disregarding  for  the 
present  the  supply  from  littoral  springs,  and  considering  only  the  supply 
from  rivers,  we  may,  by  the  aid  of  these  considerations,  deduce  from  the 
table  tlie  time  necessary  to  store  up  in  the  lake  the  observed  amount  of 
each  of  its  mineral  constituents.  The  results  of  such  comj)utation  appear 
in  the  right-hand  column  of  the  table. 

One  of  the  most  conspicuous  features  of  these  results  is  their  variety. 
The  streams  carry  enough  calcium  to  charge  the  lake  to  the  observed  extent 
in  eighteen  years,  but  34,000  years  are  necessary  to  similarly  charge  it 

'  Lands  of  the  Arid  Region,  p.  72. 


256  LAKE  BONNEVILLE. 

witli  chlorine.  Tlie  explanation  lies  in  the  relative  supply  of  these  sub- 
stuuccs  and  tlieir  relative  solubility.  In  the  mountains  from  -vvhich  the 
rivers  flo\v,  calcium  is  afforded  in  luilimited  quantity,  while  the  su})ply  of 
chlorine  is  relatively  very  small.  Chlorine,  on  the  other  hand,  e-xisting  as 
it  does  in  combination  with  sodium,  is  highly  solulilc;  while  calcium,  exist- 
ing for  the  most  part  hi  combination  with  carbonic  acid,  is  sparingly  soluble. 
Chlorine  therefore  accumulates  in  the  lake,  while  calcium  is  precipitated. 
It  is  a  matter  of  observation  that  calcium  carbonate  gathers  on  the  shore 
of  the  lake  as  oolitic  sand,  and  it  is  probable  that  it  also  falls  to  the  bottom 
as  a  marly  constituent  of  the  lacustrine  sediment.  Calcium  has  therefore 
reached  its  limit  and  is  an  unvarying  constituent  of  the  brine.  The  annual 
accession  is  balanced  by  the  annual  precipitation. 

The  same  remark  applies  to  the  magnesium.  It  is  presumably  precipi- 
tated with  the  calcium,  just  as  it  was  from  the  waters  of  Lake  Bonneville, 
and  chemical  analysis  shows  that  a  small  portion  of  it  is  accumulated  in 
the  oolite  of  the  shore. 

The  short  period  necessary  to  accumulate  the  lake's  store  of  sulphuric 
acid,  490  years,  indicates  that  it,  too,  has  passed  the  saturation  limit  and  is 
being  precipitated.  It  appears  to  exist  in  the  lake  in  the  form  of  sodium 
sulphate,  and  it  is  probabl}'  precipitated  in  that  combination.  The  fact  that 
sodium  sulphate  is  discharged  from  the  lake  by  the  extreme  cold  of  winter 
indicates  that  it  must  exist  at  ordinary  temperatures  in  quantitities  not  far 
from  the  saturation  limit;  and  it  is  found  to  be  the  first  mineral  to  separate 
from  the  brine  when  evaporated  by  insolation. 

There  remain  two  substances  whose  long  accumulation  periods  permit 
us  to  doubt  whether  they  have  reach('(l  tlie  stage  in  whicli  accession  and  loss 
are  equal.  Sodium  and  chlorine,  in  their  combination  as  sodium  chloride, 
constitute  the  most  al)undant  mineral,  and  no  analysis  has  indicated  that 
the  brine  is  fully  saturated  therewith.  If  it  be  true,  as  surmised,  that  the 
annual  supply  of  sul})huric  acid  is  discharged  from  the  lake  by  the  precipi- 
tation of  sodium  sulphate,  the  accumulation  period  for  sodium  chloride  is 
not  properly  represented  by  the  period  conq)uted  for  sodium.  It  is  more 
likely  to  be  represented  by  the  period  estimated  for  the  chlorine,  namely, 
34,200  years. 


now  OLD  IS  GREAT  SALT  LAKE?  257 

If  iio\y  we  recall  to  attention  tlie  tribute  of  the  littoral  springs,  tem- 
porarily ignored,  it  is  at  once  apparent  that  onr  table  nnderestiniates  the 
annual  tribute  of  sodium  chloride  and  corres])ondingly  overestimates  its 
accumulation  period.  We  have  no  present  means  of  determining  the  extent 
of  this  ovei'estimate,  but  Ave  can  safely  say  that  the  period  necessary  to 
charge  the  lake  with  common  salt  by  means  of  the  present  sources  and  rate 
of  supply  is  not  more  than  25,000  years.  Shall  we  conclude  that  25,000 
years  ago  the  lake  was  fresh?  or  is  there  reason  to  believe  that  sodium 
chloride,  like  the  other  constituents,  is  being  precipitated  by  the  lake  as 
rapidly  as  received?  To  this  question  a  satisfactory  answer  can  not  be  given, 
but  there  are  several  considerations  favoring  the  second  alternative.  First, 
the  circumstances  coimected  with  the  old  storm  line,  to  which  reference  has 
already  been  made,  indicate  that  the  lake  was  smaller  and  therefore  more 
concentrated,  for  at  least  a  few  decades  preceding  the  settlement  of  the 
country,  than  it  has  been  since.  It  may  Avell  be  that  a  portion  of  the  salt 
was  thrown  down  during  this  preliistoric  period,  and  that  it  was  condjined 
with  mechanical  sediment  in  sucli  way  as  to  be  preserved  from  resolu- 
tion. Second,  it  is  known  that  under  special  circumstances  salt  is  now 
precipitated  at  some  points  on  the  margin  of  the  lake.  Where  a  broad 
expanse  of  water  near  the  shore  is  exceedingly  shallow,  the  local  evapora- 
tion is  not  compensated  by  the  circulation,  and  the  resulting-  high  concen- 
tration leads  to  a  discharge  of  salt.  In  passing  from  Grantsville  to  Stansbury 
Island  in  1881,  Mr.  Russell  rode  for  a  mile  across  a  deposit  of  this  character 
an  inch  in  thickness.  Such  a  deposit  as  this  would  vmdoubtedly  be  redis- 
solved  if  the  lake  rose,  or  if  it  fell  so  as  to  permit  the  action  of  rain;  but 
the  fact  of  its  formation  indicates  how  triAdal  are  the  conditions  which  may 
determine  precipitation.  On  the  whole,  it  is  not  unreasonable  to  suppose 
that  each  of  the  minima  which  occur  in  the  ordinary  history  of  the  oscilla- 
tions of  the  lake  marks  an  epoch  of  precipitation,  when  a  portion  of  the 
saline  matter  is  discharged  .and  a  smaller  portion  is  so  combined  with 
other  sediments  as  to  remain  a  permanent  deposit.  While  it  can  not  be 
true  that  the  annual  precipitation  counterbalances  the  annual  supply,  it 
is  quite  conceivable  that  a  century's  precipitation  disposes  of  a  century's 
supply. 

MON   I 17 


258  LAKE  BONNEVILLE. 

There  seems  thus  a  possibility,  if  not  indeed  a  j)r()l)ability,  that  none 
of  the  substances  which  have  been  ([uantitatively  determined  in  the;  Ijrine 
and  in  the  tributary  rivers  are  undergoing  accunudation  in  th(!  lake;  ])ut  it 
does  not  foUow  tliat  this  equation  of  supply  and  discharge  h;is  sid)siste(l  for 
a  long  period.  There  are  certain  soluble  l)ut  very  rare  substances,  such  as 
the  comjiounds  of  Ijoron,  lithium,  iodine  and  bi-omine,  which  tend  to  accu- 
mulate in  inland  lakes  of  great  antiquity  and  have  come  to  be  regarded  as 
the  diagnostic  characters  of  age.  Only  one  of  these  has  been  detected  in 
the  water  of  Great  Salt  Lake,  and  that  one  is  not  found  in  measurable 
quantity.  The  conclusion  that  the  brine  is  recently  accumulated  accords 
with  the  facts  derived  from  the  Bonneville  history,  for  at  the  time  of  the 
outflow  the  salts  stored  in  the  lake  must  have  been  discharged  beyond  the 
limits  of  the  basin.  The  age  of  the  Gi'eat  Salt  Lake  brine  can  not  then  be 
greater  than  the  antiquity  of  the  second  Bonneville  flood. 

We  might  conclude  that  the  age  of  the  brine  is  precisely  equal  to  the 
antiquity  of  the  Bonneville  flood  were  it  not  for  the  possibility  that  the  lake 
has  since  then  been  freshened  by  desiccation.  Russell  finds  excellent  reason 
to  believe  that  in  the  Lahontan  basin,  which  is  in  many  respects  a  duplicate 
of  the  Bonneville,  the  flood  epoch  has  been  followed  by  one  of  very  low 
ebb,  in  which  the  residuaiy  lakes  have  so  dried  away  that  all  their  saline 
matter  lias  become  entangled  with  mechanical  sediment.^  A  more  recent 
accession  of  water  has  produced  a  number  of  slightly  brackish  lakes,  whose 
feeble  brines  contain  in  their  constituents  no  hint  of  great  age.  If  the 
Salt  Lake  basin  has  passed  through  a  similar  recent  epoch  of  desiccation,  it 
is  not  easy  to  see  how  we  should  become  cognizant  of  it.  Provided  the 
antiquity  of  the  epoch  was  sufficient  to  permit  the  subsequent  accunudation 
of  the  sodium  chloride,  the  character  of  the  brine  would  be  sub.stantially  as 
we  find  it.  For  the  present,  at  least,  we  must  regard  it  as  an  open  ques- 
tion whether  the  existing  lake  with  its  characteristic  brine  dates  from  the 
cessation  of  Bonneville  overflow  or  from  a  subsequent  epoch  of  extreme 
aridity. 

Fauna.-The  animal  life  of  the  lake  has  been  described  by  Packard, 
who  finds  it  to  consist  ot  two  species  only,  a  brine  shrinq),  Artvmia  yraciHs- 

'  Geol,  Hist,  of  Lake  Lahoutau,  ]ip.  2'H-i'iO. 


THE  BKINE  SHKIMP,  259 

Verrill/  and  the  larva  of  a  fly,  Epln/did  (/racilis  Packard.  Tlieso  are  very 
abundant  in  certain  seasons  of  the  year.  They  feed  upon  alga',  of  which 
three  species  have  been  recognized.  The  meagerness  of  tliis  fauna  is  to  be 
ascribed  tt)  the  rarity  among  animal  sj)ecies  of  the  power  to  li\'e  in  concen- 
trated brine.  Packard  ascribes  the  phenomenal  abundance  of  the  Artemia 
to  the  absence  of  enemies,  for  the  brine  sustains  no  carnivorous  species  of 
anv  sort.  The  genus  is  not  known  to  live  in  fresh  water  or  water  of  feeble 
salinity,  but  it  connnonly  makes  its  appearance  when  feebly  saline  waters 
are  concentrated  by  evaporation.  It  has  been  ascertained  that  a  European 
species  takes  on  the  characters  of  another  genus,  Branchinecta,  when  it  is 
bred  through  a  series  of  generations  in  brine  gradually  diluted  to  freshness, 
and  conversely,  that  it  may  be  derived  from  Branclihieda  by  gradual 
increase  in  the  salinity  of  the  medium.  It  is  found,  moreover,  tliat  its  eggs 
remain  fertile  for  indefinite  periods  in  the  dry  condition,  so  that  whatever 
may  have  been  the  history  of  the  climate  of  the  Bonneville  Basin,  the 
present  occurrence  of  the  Artemia  involves  no  mystery.  During  the  Bonne- 
ville epoch  its  ancestors  may  have  lived  in  the  fresh  waters  of  the  basin, 
and  during  the  epoch  of  extreme  desiccation,  when  the  l)ed  of  Great  Salt 
Lake  assumed  the  playa  condition  and  was  diy  a  portion  of  the  year, 
the  persistent  fertility  of  its  eggs  may  have  preserved  the  race.  Or,  if  the 
playa  condition  with  its  concomitant  sedimentation  was  fatal  to  the  species, 
it  may  be  that  the  alternative  fresh  water  form  survived  in  upper  lakes  and 
streams  of  the  basin,  so  as  to  restock  the  lower  lake  whenever  it  aftbrded 
favorable  conditions. 

THE  GESTKRALi  HISTORY  OF  BONNE VIIiLE  OSCIIjIjATIONS. 

We  may  now  assemble  the  conclusions  derived  froni  the  discussions  in 
preceding  chapters  and  in  the  j^receding  sections  of  this  chapter,  and  exhibit 
a  complete  history  of  the  oscillation  of  lake  surface  within  tlie  Bonneville 
Basin,  so  far  as  it  is  known. 

The  relation  of  the  alluvial  cones  to  the  shore-lines,  and  the  condition 
of  the  low  passes  on  the  rim  of  the  basin,  show  that  before  the  Bonneville 

'  A  monograph  of  the  Phyllopod  Crustacea  of  North  America.  By  A.  S.  Packard,  Jr.  U.  S. 
Geol.  and  Geog.  Surv.  of  the  Terr.  12th  Ann.  Kept.,  Part  1,  1883,  pp.  295-592.  Artemia  graciUa  on  pp. 
330-334. 


260  LAKE  BONNEVILLE. 

flooding'  the  water  level  was  low.  This  we  may  call  the  pre-Bonneville 
low-water  epoch.  It  was  of  great  duration  compared  with  those  enumer- 
ated below. 

The  first  Bonneville  epoch  of  higli  water  is  stratigraphically  repre- 
sented by  the  Yellow  Clay.  Peculiarities  of  the  shore-lines,  and  the  })he- 
nomena  at  Red  Rock  and  other  passes,  shoAV  that  the  water  did  not  rise  to 
the  rim  of  the  basin  and  was  not  discharged. 

After  the  deposition  of  the  Yellow  Clay  the  water  subsided,  and  the 
basin  was  nearly  or  perhaps  completely  desiccated.  The  stratigraphic  evi- 
dence of  this  subsidence  is  found  in  the  unconformity  betAveen  the  Yellow 
Clay  and  the  White  Marl  and  in  the  alluvial  deposits  occurring  at  that 
horizon.  The  possibility  of  complete  desiccation  is  suggested  by  the  differ- 
ence in  character  between  the  antecedent  and  subsequent  deposits,  Avhich 
difference  may  have  been  occasioned  by  a  change  in  the  conditions  of  sedi- 
mentary precipitation.  This  may  be  called  the  iuter-Bouneville  epoch  of 
low  water. 

The  second  Bonneville  epoch  of  high  water  is  represented  stratigraph- 
ically by  the  White  Marl.  Before  the  close  of  the  epoch  the  water  over- 
flowed at  Red  Rock  Pass,  forming  a  channel  of  outflow  which  was  excavated 
to  a  depth  of  375  feet.  The  Bonne\'ille  shore-line  records  the  water  surface 
at  the  date  of  initial  outflow.  The  Provo  shore-line  records  its  position 
after  the  channel  of  outflow  had  attained  its  maximum  depth. 

The  existing  state  of  affairs  was  brought  about  by  the  recession  of  the 
lake  surface  from  the  Provo  shore,  and  is  stratigraphically  re})resented  by 
the  formation  of  local  alluvial  deposits  on  the  sui-face  of  the  White  Marl. 
The  sedimentary  deposits  and  shore  embankments  marking  the  high- water 
stages  have  been  more  or  less  eroded  by  the  modem  streams,  and  the  ancient 
deltas  especially  have  been  deeply  trenched.  The  basin  has  been  diA-ided 
into  a  number  of  minor  hydrographic  units.  This  modern  epoch  may  be 
called  the  post-Bonneville  epoch  of  low  water. 

Nothing  is  known  of  the  absohite  duration  of  these  epochs,  and  in  the 
study  of  their  relative  duration  no  trustworthy  means  has  been  found  for 
comparing  a  high-water  epoch  with  a  low-Avater  epoch.  The  deposit  mark- 
ing the  first  high-water  epoch  is  thicker  than  that  marking  the  second,  and 


SUMMARY  OP  BONNEVILLE  HISTORY.  261 

we  may  hence  conclude  that  the  first  epoch  was  the  hinger,  but  the  amount 
of  this  difference  is  rendered  indefinite  by  the  fact  that  the  base  of  the 
lower  deposit  is  not  exposed.  The  comparison  is  further  comphcated  by 
the  difference  in  the  two  deposits,  the  lo^ver  containing  in  the  center  of  the 
basin  a  larger  per  cent,  of  clay  than  the  upper.  If  it  be  true  that  the  water 
was  so  constituted  during  the  second  flood  as  to  precipitate  a  relatively 
large  share  of  the  clay  near  the  shore,  and  that  the  difference  of  constitu- 
tion did  not  affect  the  precipitation  of  the  calcareous  matter,  a  time  ratio 
may  be  based  upon  the  calcareous  factors  of  the  two  elements  of  the 
exposed  section.  A  computation  under  this  postulate  indicates  that  the 
first  high-water  epoch  was  not  less  than  five  times  as  long  as  the  second. 

Data  do  not  exist  for  the  quantitative  estimation  of  the  relative  dura- 
tion of  the  low-water  epochs,  but  their  order  of  magnitude  is  unmistakable. 
A  comparison  of  the  few  alluvial  wedges  referable  to  the  inter-Bonneville 
epoch  with  their  local  representatives  formed  during  the  post-Bonneville 
epoch  shows  the  former  to  be  invariably  the  larger,  and  indicates  that  the 
time  between  the  two  Bonneville  floods  was  longer  than  post-Bonneville 
time.  The  pre-Bonneville  low- water  epoch  represented  by  the  great  alluvial 
cones  of  the  movmtain  flanks  is  still  less  amenable  to  numerical  statement, 
in  that  its  beginning  is  undefined;  but  it  is  unquestionable  that  it  far  tran- 
scended in  length  the  inter-Bonneville  epoch. 

It  will  be  observed  that  in  all  respects  our  knowledge  of  the  high-water 
epochs  is  relatively  definite.  Not  only  are  we  able  a^jproximately  to  com- 
jiare  tlie  two  high-water  epochs  in  duration,  but  we  know  that  on  the  sec- 
ond occasion  the  water  rose  higher  than  on  the  first.  But  of  the  decree  of 
desiccation  attained  in  the  pre-Bonneville  and  inter-Bonneville  epochs  we 
are  practically  without  information.  We  have  observed  and  approximately 
determined  two  important  maxima  of  an  undulating  curve,  and  have  dem- 
onstrated that  they  are  the  only  great  maxima  of  the  curve;  but  we  know 
practically  nothing  of  the  remainder  of  the  curve  and  are  unable  to  indicate 
the  position  of  any  minima,  properly  .so  called. 

The  knowledge  we  have  gleaned  is  graphically  exhibited  in  Fig.  34, 
where  the  upper  and  lower  horizontal  lines  represent  the  horizons  of  the 
Bonneville  shore  and  the  surface  of  Great  Salt  Lake.     Horizontal  distances 


262  LAKE  BONNEVILLE. 

represont  time,  counted  t'roni  left  to  right.     'J'lie  curve  represents  tlie  lieig-lit 
of  tlie  oscilliiting  water  surface,  and  the  shaded  area  indicates  ignoi'ance. 


Fig.  34. — Rise  and  Fall  of  water  in  the  Bonuovillo  Basin. 
THE  TOPOGRAPHIC  INTERPRETATION  OF  LAKE  OSCILLATIONS. 

(!)ne  of  the  most  important  siilijects  to  ■wliicli  the  discussion  of  the  Bon- 
nevilk'  history  sliouhl  contribute  is  tliat  of  geologic  climate.  The  oscilla- 
tions of  the  lake  were  in  all  })ro]iability  caused  ])y  oscillations  of  climate; 
and  if  we  can  satisfy  ourselves  as  to  the  nature  of  the  |)articular  climatic 
movements  associated  witia  the  rise  and  the  fall  of  the  lake,  we  can  imme- 
diatel}',  by  changing  the  notation  of  oin-  curve,  convert  it  into  a  record  of 
geologic  climate.  But  in  order  to  be  fully  satisfied  that  the  curve  has  cli- 
matic .significance,  it  is  necessary  at  the  outset  to  give  consideration  to  other 
possible  modes  of  interpretation.  For  this  purpose  we  revert  once  more  to 
the  fundamental  conditions  controlling  the  size  of  a  closed  lake.  The  size 
depends  on  the  ratio  between  the  suj)ply  of  water  and  the  rate  of  evapora- 
tion. Rate  of  evaporation  is  purely  a  function  of  climate;  but  water  supply 
depends  quite  as  much  on  topographic  configuration  as  on  meteorologic 
conditions.  We  are  therefore  called  upon  to  inrpiire  whether  the  water 
su})ply  of  the  Bonneville  Basin  may  have  been  modified  by  to})Ographic 
changes  in  such  way  as  to  account  for  the  demonstrated  rise  and  fall  of  the 
lake. 

It  is  conceivable,  first,  that  local  oscillations  of  land  surface,  or  volcanic 
eruption,  or  the  Inu'sting  of  barriers  may  at  one  time  have  increased  the 
Bonneville  drainage  district  at  the  expense  of  some  other  district,  and  mav 
afterwards  have  diminished  it.  It  is  conceivable,  second,  that  crust  move- 
ments may  have  affected  the  altitude  of  the  nimuit.iins  whence  the  wati'r 
supply  of  the  basin  floAvs,  in  such  way  as  to  cause  them  to  intercept  a  greater 
share  of  atmospheric  moisture  at  some  times  than  at  others.     It  is  conceiva- 


WHAT  CONTEOLLED  THE  WATER  SUITLY?  263 

ble,  third,  that  still  grander  crust  movements  have,  by  raising  and  lowering 
a  great  area  including  the  basin,  produced  corresponding  modifications  of 
its  general  climate. 

Hydrographic  Hypothesis.-Tlie  posslbility  that  tlic  Bomievillc  drainage  district 
has  gained  or  lost  Ijy  the  slow  shifting  of  water  partings  or  the  diversion  of 
rivers  has  already  been  considered  in  the  first  section  of  this  chapter;  and 
it  is  there  shown  that  the  only  important  changes  it  is  admissible  to  postu- 
late are  such  as  affect  the  supply  afforded  by  Bear  River.  It  is  quite  pos- 
sible that  the  Blackfoot,  which  now  belongs  to  another  drainage  district, 
once  contributed  its  waters  to  the  Bear;  and  on  the  other  hand,  it  is  quite 
possible  that  the  main  trunk  of  the  Bear  was  once  turned  from  the  Bomie- 
ville  Basin  to  that  of  the  Columbia;  but  the  first  of  these  possibilities  is 
quantitatively  and  the  second  is  qualitatively  inadequate  to  explain  the 
Bonneville  oscillations.  If  the  Blackfoot  were  now  to  be  restored  to  the 
Bear  River,  there  would  result  an  increase  in  the  area  and  depth  of  Great  Salt 
Lake,  but  such  change  is  not  to  be  compared  in  magnitude  with  the  changes 
involved  in  the  Bonneville  history ;  the  depth  of  the  lake  would  be  increased 
only  five  or  ten  feet  at  most.  If  the  main  trunk  of  Bear  River  were  to  be 
converted  into  a  tributary  of  the  Columbia  a  more  important  result  would 
be  produced,  but  the  Bonneville  status  would  not  be  restored;  on  the  con- 
trary, the  area  and  depth  of  Great  Salt  Lake  would  be  diminished. 

It  may  be  added  that  the  condition  of  the  basaltic  sheets  occupying 
tlie  passes  Ijetween  the  Bear  River  and  the  tributaries  of  the  Columbia  does 
not  indicate  that  they  are  sufficiently  recent  to  be  appealed  to  in  ex])lana- 
tion  of  the  changes  during  the  Bonneville  epoch.  There  are  lavas  within 
tlie  lake  area  which,  judged  by  their  condition  with  respect  to  weathering, 
are  newer  than  those  on  the  northern  passes,  and  yet  are  demonsti'ably 
older  than  the  epoch  of  the  Yellow  Clay. 

orogenic  Hypothesis.-Thc  mouutains  affordiug  the  chief  Avater  supjjly  of  the 
basin  are  the  Wasatch  and  the  Uinta.  The  Wasatch  is  known  to  have  in- 
creased in  height,  by  faidting,  since  the  last  Bonneville  flood,  and  both 
ranges  are  known  to  have  been  somewhat  u])lifted  since  the  deiDOsition  of 
Neocene  strata.  It  is  highly  probable  that  they  ex])erienced  upward 
movements  during  Pleistocene  time;  and  it  is  indubitable  that  every  such 


264  LAKE  BONNEVILLE. 

movement  would  result  in  an  increase  of  the  local  precipitation  and  of  the 
consequent  mag-nitude  of  the  streams.  On  the  other  hand,  it  is  hig-jily  iin- 
prohable  that  either  of  these  mountains  has  been  subject  to  displacements 
of  such  nature  as  to  reduce  its  height.  The  conjoint  influence  of  rhythmic 
upheaval  and  equable  degradation  undoubtedly  produces  alternate  gains  and 
losses  in  altitude,  and  there  must  be  corresponding  gains  and  losses  in  the  pre- 
cipitation and  outflow ;  but  however  plausible  such  a  hypothesis  may  appear 
ni)()ii  a  merely  qualitative  statement,  it  must  be  regarded  as  quantitatively 
inadequate.  We  have  an  approximate  measure  of  the  extent  of  the  degra- 
dation in  the  lacustrine  deposits  which  derive  their  material  chiefly  from 
that  source,  and  we  can  not  suppose,  for  example,  that  the  removal  of  the 
entire  mass  of  the  White  Marl  from  the  uplands  at  the  east  would  sufficiently 
aff'ect  their  altitude  to  diminish  the  water-supidy  of  the  basin  as  it  has  been 
diminished  since  the  White  Marl  epoch. 

There  is,  moreover,  a  general  objection  to  any  explanation  appealing 
to  merely  local  changes,  whether  of  drainage  or  altitude.  The  history  of 
Lake  Lahontan,  as  developed  by  Russell,  corresponds  in  a  remarkable  way 
with  that  of  Bonneville.  It  includes  two  maxima  and  two  only,  the  first 
being  the  longer  and  the  second  the  higher.^  It  is  therefore  in  a  high  de- 
gree probable  that  the  phenomena  have  a  common  cause,  and  such  cause 
must  be  of  a  general  nature. 

Epeirogenic  Hypothesis.-Tliis  difficulty  is  oscapcd  by  the  third  hypothesis,  in 
which  a  large  area,  including  both  lake  basins,  is  conceived  to  have  been 
siiccessively  elevated  and  depressed  to  an  extent  sufficient  to  reform  its 
climate.  Of  the  adequacy  of  such  a  cause  there  can  ])e  no  question,  l)ut  we 
are  without  evidence  of  its  actuality.  There  are,  indeed,  in  the  basins  of 
the  Columbia  and  Frazer,  systems  of  terraces  indicative  of  recent  changes 
in  the  relation  of  the  ocean  to  the  continent;  but  these  serve  only  to  indi- 
cate the  fact  of  wide-spread  change  and  do  not  demonstrate  sucli  changes 
as  are  necessary  to  account  for  the  flooding  of  the  Lahontan  and  Bonneville 
Basins.  If  that  flooding  is  the  index  of  a  local  climate  wrought  ])y  conti- 
nental movement,  the  humid  condition  should  theoretically  be  the  result  of 
continental  elevation  and  the  last  change  should  have  been  a  subsidence; 

'  Geol.  Hist,  of  Lake  Lahontan,  p.  237. 


OPINIONS  ON  CORRELATION  OF  LAKES  AND  GLACIERS.       265 

whereas,  in  the  basins  of  the  Cokimbia  and  Frazer,  tlie  hist  chanjre  appears 
to  have  ])een  an  elevation. 

Since  the  suggested  continental  movements  could  affect  tlie  lakes  only 
through  the  mediation  of  local  climate,  the  hypotliesis  which  appeals  to  them 
is  essentiall)'  a  climatic  hypothesis;  and  its  further  consideration  may  be 
deferred  until  its  proper  place  is  reached  in  the  discussion  of  the  intluence 
of  changes  in  terrestial  climate. 

THE  ClilMATIC  INTERPRETATION  OF  LAKE  OSCILtiATIONS. 

OPINIONS  ON  CORRELATION   WITH  GLACIATION. 

Turning  now  to  the  subject  of  climatic  interpretation,  we  find  an  almost 
universal  agreement  among  geologists  in  the  view  that  the  lake  maxima 
were  in  some  way  associated  with  the  history  of  glaciation.  Tlie  idea  tliat 
the  rise  of  a  lake  contained  in  a  closed  basin  is  a  phenomenon  properly  cor- 
related with  the  formation  or  extension  of  glaciers  appears  to  have  been 
independently  suggested  by  Jamieson,  Lartet,  and  Whitney.  Jamieson, 
speaking  in  1863  of  the  climate  of  Central  Asia,'  said: 

The  great  basin  of  the  continental  streams,  larger  than  the  area  of  Europe,  is 
remarkable  for  its  inland  lakes  from  whence  no  streams  ever  reach  the  ocean,  owing 
to  the  great  heat  drying  up  tlie  water.  Now  this  heat  and  dryness  being  much  lessened 
during  the  glacial  period,  there  must  have  resulted  a  much  smaller  evaporation,  which 
would  no  longer  balance  the  indow.  These  lakes  therefore  would  swell  and  rise  iu 
level,     .     .     . 

Two  years  later,  Lartet  wrote: 

Tlie  level  of  tlie  Dead  Sea  must  therefore  have  been  constantly  regulated  by  the 
conditions  of  equilibrium  between  atmospheric  preci[iitation  and  evaiioration.  The 
extension  of  the  waters  of  this  lake,  at  a  certain  e[ioch,  revealed  by  the  sediments 
now  laid  bare,  which  cover  such  vast  surfaces  to  the  north  and  to  the  s.uth  of  its 
present  limits,  bears  witness  to  a  great  change  supervened  since  then  iu  the  atmos- 
pheric conditions  to  which  the  liydrograpliic  regime  of  the  country  was  subjected. 
In  the  absence  of  fossils  in  the  sediments  anciently  dei)osited  by  the  lake,  it  is 
impossible  to  assign  a  i)recise  age  to  the  elevation  of  its  waters.  However,  taking 
account  of  the  probable  duration  of  the  phenomena  which  must  have  preceded  and 
followed  this  important  phase  of  the  history  of  the  Dead  Sea,  one  would  be  led  to 
attribute  to  it  a  date  close  to  the  end  of  the  Tertiary  and  the  beginning  of  the  Quatei- 

'Ou  tlie  parallel  roads  of  Glen  Roy  and  their  place  in  the  history  of  the  glacial  period,  by  Thomas 
F.  Jamieson,  Quarterly  Journal  Geological  Soc,  Loudon,  vol.  19,  pp.  235-259.  The  passage  cited 
occurs  on  p.  258. 


266  LAKE  BONNEVILLE. 

nary  poriod.  Ono  would  thou  bo  alilo  to  soo  in  tliis  riso  of  tlic,  surface,  of  tlio  lake  an 
ettect  of  the  glainal  plieiiomeiia  whose,  iritliieiice  seems  to  have  extiMidecl,  at  tliese 
epochs,  to  ueighboriug  resioiis.  Tliis,  inor(M)ver,  would  accord  ipiite  well  with  the 
observation  of  traces  of  ancient  moraines  which  Dr.  D.  Hooker  tliought  he  recognized 
on  the  slopes  of  Lebanon.' 

Only  a  few  months  later,  Whitney,  treating,  in  the  first  volume  of  the 
Geology  of  California,  of  the  former  extension  of  ^Mono  Lake,  said: 

Whatever  cause  gave  rise  to  the  immense  body  of  ice,  in  the  form  of  glaciers, 
which,  as  we  have  seen,  formerly  covered  the  summit  of  the  Sierra  in  this  region  and 
extended  down  for  5,000  feet  or  more  from  the  crest,  this  would  undoubtedly  have 
been  snfticient  to  siipi)ly  water  enough  to  raise  the  lake  to  the  height  which  the  ter- 
races about  it  show  that  it  must  once  Iiave  liad.- 

It  is  not  certain  tliat  he  adheres  to  this  view  at  present,  for  in  his 
memoir  on  the  Climatic  Changes  of  Later  Geological  Times  (1882),  he 
characterizes  the  glaciation  of  the  Sierra  as  an  episode  (p.  2),  but  regards 
the  desiccation  of  the  Great  Basin  as  a  continuous  process  of  which  the 
beginning  dates  far  beyond  the  Pleistocene.     On  p.  190  he  says: 

Before  advancing  another  stage  in  our  discussion,  however,  we  have  to  make  it 
clear  that  the  diminution  of  the  rivers,  the  disappearance  of  the  lakes,  and  all  the  other 
phenomena  indicative  of  a  gradual  but  persistent  tendency  to  aridity  over  vast  areas 
once  fertile  and  well  watered,  do  not  form  a  transient  i)hase  of  a  precedent  Claeial 
epoch,  but  are  the  result  of  some  cause  which  began  to  act  before  that  period,  and  is 
still  continuing  without  any  connection  with  it. 

In  my  original  description  of  Lake  Bonneville  I  argued  its  correlation 
with  the  Pleistocene  Period  in  the  following  language: 

The  Bonneville  epoch  and  the  Glacial  epoch  were  alike  climatal  episodes,  and 
they  oci  urred  in  the  same  general  division  of  geological  time,  namely,  the  division  of 
which  modern  time  is  the  immediate  sequel.  If  it  can  be  .«hown  that  the  climatic 
changes  were  of  the  same  kind,  there  need  be  no  hesitation  in  assuming  the  identity 
of  the  epochs.  The  glacial  climate  we  commonly  regard  as  merely  cold,  and  a  low 
temperature  was  doubtless  its  chief  characteristic;  but  it  admits,  ne  ertlieless,  of 
another  view,  The  climatic  comlition  essential  to  the  formation  of  glaciers  is,  tint 
the  summer's  heat  shall  be  inadequate  to  dissipate  th(>  winter's  snow,  and  this  may  lie 
brought  about,  either  by  a  lowering  of  temperature,  or  by  an  increase  of  winter  pre- 
ci[)itatio;i.  The  jirofuse  |)recipitation  of  our  northwestern  coast  woultl  maintain  s'leat 
glaciers  if  the  climate  were  cold  enough;  rivers  of  ice  would  follow  the  higher  valleys 
of  the  Rocky  Mountains  if  the  snow-fall  were  heavy. 


'Louis  Lartot,  Comptcs  Roiuliis  <lo  rAcaddniio  ilcs  Sciouces,  Paris,  St^anco  du  17  Avril,   18Go. 
Vol.  CO,  p.  798. 

Seo  also  Hull,  de  la  .Soc.  Gfi.o\.  do  la  Frauic,  '2(1  sftric,  vol.  22,  p.  4,")7 ;  Si'aiuo  <lu  1  Mai,  186.5. 
«Geol.  of  Cal.,  vol.  1,  p.  452. 


OPINIONS  ON  CORRELATION  OF  LAKES  AND  GLACIERS.        267 

To  account  for  the  origin  of  Bonneville  Lake,  we  need  to  assume  a  climatal 
change,  that  would  increase  in-ecipitation,  or  diminish  evaporation;  and  both  of  these 
ctlVc's  would  follow,  in  accordinici^  with  familiar  meteorological  laws,  if  the  luiiiiidity 
of  the  air  were  increased,  or  if  the  temperature  were  lowered.  There  can  be  no  doubt, 
then,  that  the  great  climatal  revolution,  which  covered  our  northeastern  States  with 
ice,  was  competent  to  flood  the  dry  basin  of  Utah;  and  that  it  actually  did  so  is  at 
least  highly  probable.' 

In  volume  1  of  the  Fortieth  Parallel  report  (1878)  King-  classified  Lake 
Lahontaii  as  well  as  Lake  Bonneville  as  a  phenomenon  of  the  Pleistocene 
or  Quaternary  period,  and  argued  that  their  basins  were  di'y  at  the  beginning 
of  the  period.  In  the  case  of  Lake  Lahontan,  from  a  discussion  of  the 
chemical  history  of  a,  jjcculiar  pseudomorijh,  thinolite,  lu;  drew  the  conclu- 
sion that  the  basin  was  flooded  twice  instead  of  once,  the  first  flooding  hav- 
ing "an  enormously  long  continuance  as  compared  with  the  second."  He 
further  concludes: 

The  first  long-continued  period  of  humidity  is  jirobably  to  he  directly  correlateil 
with  the  earliest  and  greitest  Glacier  period,  and  the  second  period  of  humidity  with 
the  later  Ri'indeer  Glacier  period. 

The  Quaternary  lakes  of  the  Great  Basin  are  therefore  of  extreme  importance  in 
showing  one  thing — that  the  tw(j  glacial  ages,  whatever  may  have  been  their  temi)er- 
ature  conditions,  were  in  themselves  each  distinctly  an  age  of  moisture  and  tl  at 
the  interglacial  period  was  one  of  intense  dryness,  eciual  in  its  aridity  to  the  jiresent 
epoch  .^ 

I  afterward  discovered  the  evidence  of  the  inter-Bonneville  epoch  of 
low  water,  and  thus  demonstrated  the  duality  of  the  Bonneville  flooding. 
Announcing  this  discovery  in  the  First  Annual  Rej^ort  of  the  U.  S.  Geolog- 
ical Survey  (p.  26),  I  say: 

If  it  be  true,  as  argued  by  Mr.  King  and  the  writer,  that  the  Bonneville  epoch 
was  synchronous  with  the  glacial  epoch,  then  it  may  also  be  true  that  the  subdivision 
of  the  glacial  epoch  into  two  subepochs,  with  an  interval  of  warmth,  finds  here  a 
manifestation. 

Subsequent  investigations  in  the  Lahontan  basin  by  Russell  serve  to 
call  in,  question  King's  conclusions  in  regard  to  thinolite,  but  independent 
reasons  were  found  for  afiirming  the  double  maximum  of  the  lake  stirface.^ 

Peale,  who  examined  the  Bonneville  sediments  in  Malade  and  Cache 
Valleys,  does  not  discuss  their  relation  to  glaciers  or  climate,  but  may  per- 

'Explor.  West  of  the  lOOfli  Meriilian,  vol.  :?  ji.  97. 

2Geol.  Expl.  40th  P.TraUel,  vul.  1,  p.  524. 

=  Thir(l  Ann.  Rept.  U.  S.  Geol.  Survey,  pp.  2-20-222;  Geol.  Hist,  of  Lake  L,ahontau,  pp.  250-2G8. 


268  LAKE  BONNEVILLE. 

Imps  be  considered  to  im))ly  a  eon-elation,  in  tiiat  lie  refers  them  to  the 
Pleistocene.' 

A  nnicpie  view  of  the  siiliject  entertained  by  Endlich  can  not  be 
igiiovcd  in  this  connection,  and,  since  it  is  found  necessary  to  dissent  tliere- 
froin,  fixirness  seems  to  require  its  presentation  somewhat  fully  in  his  own 
language.  Speaking  of  the  ancient  glaciers  of  the  mountains  of  (Colorado, 
he  says: 

If  we  study  the  country  adjacent  to  tliat  where  we  find  glacial  evidence,  we  will 
ooserve  that  a  by  far  larger  area  was  at  one  time  covered  by  water  than  to-day. 
The  Great  Salt  Lake  extended  beyond^  the  boundaries  that  now  confine  it,  *  *  »  • 
Here,  then,  we  have  a  source  of  moisture  far  exceeding,  in  quantity,  that  carried  east- 
ward at  present  by  the  prevailing  westerly  winds.  *  »  •  i  conclude,  therefore, 
that  the  ancient  glaciers  of  Colorado  and  regions  similar  to  it,  both  as  regards  geo- 
graphical location  and  orographic  construction,  owe  their  former  existence  mainly  to 
the  presence  of  those  numerous  sheets  of  water  farther  west.  These  have  now  disap- 
peared, and  incident  upon  their  removal,  whatever  may  have  produced  that,  was  tiie 
recession  and  final  extinction  of  the  ancient  glaciers.  Holding  this  view,  I  maintain 
that  the  lakes  formerly  filling  so  many  valleys  were  in  existence  before  any  glaciers 
occurred  in  the  Rocky  Mountains  proper.  *  *  *  It  is  highly  probable,  however, 
that  the  i)eriod  of  their  greatest  magnitude  fell  into  the  time  of  the  general  glacial 
ei)Och.^    »     #     # 

A  fiital  difficulty  here  is  a  failure  to  recognize  the  fundamental  dif- 
ference between  closed  and  drained  basins  in  their  relation  to  the  moisture 
of  the  atmosphere.  Closed  basins  return  to  the  air  just  as  niucli  water  as 
they  receive  from  it;  drained  basins  do  not.  The  -prevailing  westerly 
Avinds  to  which  he  refers  sweep  across  the  hydi'ographic  district  of  the  Great 
Basin  before  reaching  the  momitains  of  Colorado.  At  the  present  time  the 
moisture  they  discharge  in  crossing  the  Great  Basin  is  precisely  equal  to 
that  which  they  absorb,  so  that  they  approach  Colorado  with  huniiditv 
unchanged.  When  Lake  Bonneville  and  some  other  lakes  of  the  basin 
were  so  filled  as  to  overflow  to  the  ocean,  the  preci.se  amount  of  their  dis- 
charge was  abstracted  from  the  westerly  winds  in  their  passage,  so  that  the 
winds  left  the  district  of  the  l^asin  drier  tlian  they  entered  it.  If  the  air 
currents  reaching  the  Colorado  Mountains  from  the  west  were  tlicii  moistcr 


■  Dr.  A.  C.  Pealc  in  Ann.  Rei>fc.  U.  S.  G.  &  G.  Snrv.  of  Terra,  for  1877,  p.  641. 
2  Dr.  F.  M.  Endlirh ;  Ann.  Kept.  U.  S.  G.  «fc  G.  Snrv.  of  Terrs,  for  187.-),  p.  S25. 


REGENCY  OF  LAKES  AND  GLACIERS.  269 

than  now,  their  humidity  must  have  been  acquired  before  they  reached  the 
district  of  the  hxkes. 

THE  ARGUMENT  FROM  ANALOGY. 

Reverting-  now  to  the  correlation  of  lacustrine  and  glacial  phenomena, 
as  suggested  and  developed  by  Jamieson,  Lartet,  Whitney,  King,  Russell, 
and  myself,  the  data  on  which  the  correlation  is  based  will  l)e  examined  in 
detail.  Up  to  the  present  time  all  reasoning  on  the  subject  has  been 
based  upon  analog  v.  The  identity  of  the  two  classes  of  phenomena  in  time 
and  cause  has  been  inferred,  tirst,  from  their  recency;  second,  from  their 
exceptional  nature;  third,  from  the  parallelism  of  their  recurrence;  and, 
fourth,  from  the  belief  that  it  is  possible  to  account  for  them  by  the  same 
modifications  of  climatic  conditions.  These  elements  of  analogy  will  be 
taken  up  in  the  indicated  order. 

Recency.-The  reccncy  of  the  lacustrine  events  and  the  recency  of  the 
glacial  events  are  severally  inferred  from  the  excellent  preservation  of  their 
vestiges.  The  atmospheric  agencies  which  sculpture  the  land,  rapidly  oblit- 
erate all  topographic  features  which  do  not  conform  to  their  types,  and  they 
attack  with  especial  vigor  masses  of  unconsolidated  material  which  stand  in 
relief.  The  embankments  of  the  ancient  shore-lines  and  the  moraines  of  the 
ancient  glaciers  agree  in  their  susceptibility  to  rapid  modification  by  erosion, 
and  they  agree  in  exhibiting  a  condition  of  almost  perfect  preservation.  In 
the  case  of  the  moraines,  this  remark  applies  onlj-  to  those  which  were  latest 
formed;  but  it  is  these  which  can  most  properly  be  compared,  for  the  earlier- 
formed  shore  embankments  are  not  visible,  having  been  overplaced  by  those 
of  later  date.  The  recency  of  phenomena  thus  demonstrated  is  qualitative 
merely:  So  far  as  we  are  able  to  interpret  the  evidence  from  preservation, 
the  embankments  may  be  twice  as  old  as  the  moraines,  or  the  moraines 
twice  as  old  as  the  embankments. 

Episodai  character.-Tlie  exccptional  iiaturc  of  the  Pleistocene  glacial  phe- 
nomena is  generally  recognized,  and  is  illustrated  in  a  striking  manner  in 
the  immediate  vicinity  of  the  Great  Basin.  As  first  pointed  out  by  Whit- 
ney, the  great  glaciers  of  the  Sierra  Nevada  occupied  an  antecedent  system 
of  valleys,  shown  by  their  form  to  be  the  product  of  stream  erosion.     The 


270  LAKE  BONNEVILLE. 

period  of  ice  was  therefore  preceded  by  h  period  wlieii  tlii're  was  no  ice,  or 
little  ice,  and  this  antecedent  period  was  of  relatively  great  duration. 

The  episodal  nature  of  the  lacustrine  j)lienoraena  of  tlie  Great  Basin 
has  been  recognized  by  all  ol)servers,  with  tlie  possil)le  exception  of  Whit- 
ney; and  the  evidence  in  relation  to  the  Bonneville  Basin  has  been  full}'  set 
forth  in  the  preceding  pages.  The  pre-Bonneville  period  was  characterized 
by  ariditv,  and  it  was  long  as  compared  to  the  Boinieville  period.  Tlie 
formation  and  extension  of  glaciers  and  the  formation  and  extension  of  lakes 
have  thus  the  common  character  of  episodes,  interrupting  a  course  of  events 
\\'hich  was  resumed  after  their  disappearance. 

Bipartition.-A  tlurd  polut  of  aualogy  is  parallelism  of  reciiiTence.  The 
history  of  Lake  Bonneville  and  the  history  of  Lake  Lahontan  have  been 
independently  shown  to  be  bipartite,  and  the  similarity  of  the  series  of 
oscillations  in  the  two  basins  gives  great  contidence  to  the  conclusion  that 
they  were  synchronous.  If  it  be  true,  as  believed  by  many  geologists,  that 
the  history  of  the  glacial  period  is  similarly  bi2)artite,  the  argument  in  fa\dr 
of  the  synchronism  and  the  common  origin  of  the  lacustrine  and  glacial 
phenomena  acquires  great  strength.  It  is  pertinent,  therefore,  to  inquire 
what  support  the  belief  in  a  double  glacial  period  finds  in  the  facts  of  obser- 
vation ;  but  since  this  inquiry  Avould  involve  too  great  a  digression  from 
the  subject  in  hand,  attention  will  be  limited  to  the  t^uestion  of  the  support 
the  belief  finds  in  the  opinion  of  those  most  competent  to  discuss  tlie 
phenomena. 

It  is  to  be  observed  at  the  outset  that  a  Ijelief  in  the  double  nature  of 
the  glacial  epoch  implies  a  belief  in  its  actuality  as  a  general  phenomenon 
of  geologic  climate.  If  the  truth  lies  with  those  who  aflinii  that  the  ancient 
glacial  phenomena  depend  upon  strictly  local  conditiinis,  and  are  not  widely 
synchronous,'  it  is  evident  that  the  bipartition  of  the  plieiionieiia  can  not  be 
general,  and  that  the  only  analogy  pertinent  to  the  present  incpiirv  would 
arise  from  the  discovery  of  evidence  of  recurrent  glacial  extension  in  the 
mountain  ranges  which  border  the  Great  Basin.     Reference  will  be  made 

'  See  J.  D.  Whitney,  Climatic  changes  cit  later  Geological  Time:  Mem.  >Siiseum  of  Compariitive 
Zoology,  vol.  7,  No.  2,  pp.  191,  21)8,  :!«7;  J.  F.  Campbell,  Glacial  periods;  Quart.  Jonrn.  Geol.  Soc. 
Loudon,  vol.  35,  p.  9K;  Rev.  James  IJrodie,  On  the  action  of  Ice  in  what  is  usually  termed  the  Glacial 
Period  :  Brit.  Ass.  Rep't,  1875,  p.  63.     (Sections.) 


EUEOPEAN  OPINIONS  ON  CIPAKTITION.  271 

ill  the  sequel  to  a  I'riigment  of  local  evidence  of  this  nature;  but  attention 
•wiW  at  present  be  restricted  to  the  testimony  in  regard  to  a  general  duplica- 
tion of  glacial  history.  The  tendency  of  the  testimony  will  be  sufficiently 
indicated  l)y  citing  those  conclusions  of  held  geologists  whidi  appear  to 
represent  the  liroadest  survey  of  phenomena  and  to  be  least  hampered  l)y 
general  theories. 

Penck,  who  has  studied  the  glacial  phenomena  of  the  northern  face  of 
the  Alps,  has  supplemented  the  presentation  of  his  own  results  l)\'  a  histori- 
cal digest  of  those  of  his  predecessors.'  He  confirms  the  recognition  by 
Morlot  and  others,  of  two  great  advances  of  the  glaciers,  and  announces 
traces  of  a  third.  The  greatest  advance  occurred  in  the  second  of  the  three 
ice  epochs,  and  the  least  advance  in  the  first. 

Briickner,  likewise  a  student  of  the  northern  face,  agrees  with  Penck 
in  recognizing  three  epochs  of  glaciation,  but  he  considers  the  first  advance 
slightly  greater  than  the  second  and  the  third  least  of  all." 

French  geologists  who  have  examined  the  western  portion  of  the  Alps 
are  practically  unanimous  in  asserting  the  unity  of  the  phenomena.  Falsan 
admits  more  or  less  protracted  phases  of  progression  and  recession  of  the 
old  glaciers,  but  denies  the  existence  of  any  adequate  evidence  of  an  inter- 
glacial  period.^ 

Those  who  have  given  special  attention  to  the  southern  or  Italian  slope 
of  the  Alps  are  divided  in  opinion.  Sto})})ani  and  Gastaldi  regard  the  gla- 
cial period  as  a  unit,^  while  Taramelli  distinguishes  two  phases  of  glacial 
expansion,  separated  by  a  long  interval  marked  by  hydrographic  changes 
and  slight  oscillations  of  level.^ 

James  Geikie  recognizes  no  fewer  than  four  glacial  epochs,  separated 
by  intervening  epochs  of  mild  climatic  conditions."     In  the  English  deposits 

'The  Glaciatiou  of  tbc  German  Alps.     .     .     .     By  Dr.  Albrecht  Penck.     pp.  220,  ^61,  311,  :5->2. 

-Die  Eiszeit  iu  deu  Alpeu.  vou  Dr.  Eduard  Briickner.  Mittheil.  Geogr.  Gesell.  Hamburg, 
1887-88,  pp.  10-12. 

^A.  Falsan,  Esquisse  gdologique  du  terrain  errati(|ue  et  des  anciens  glaciers  do  la  region  ceutralo 
dn  bassin  du  Rhone.  Lyon,  1883.  (Cited  at  second  band.)  Also,  La  piSriode  glaciaire.  Paris,  1889, 
pp.  24-2-245. 

■■A.  Stoppani,  Geologia  d'ltalia,  Part  2,  Milan,  1880.  Gastaldi,  Realo  Accademia  delle  Scienze  di 
Torino.  Atti.  1872-73.  8°.  Page  410,  "  Appuuti  sulla  Memoria  del  Sig.  Geikie  F.  R.  S.  E  ,  On  changes 
of  cliiiinte  during  the  glacial  epoch." 

sTaramelli,  Atti  della  Reale  Accademia  dei  Liucei,  1881-82,  3d  series,  vol.  13.     Roma,  18S2,  p.  508. 

^Prehistoric  Europe,  p.  2G5 


272  LAKE  BONNEVILLE. 

the  first  <j;lai-ial  epoch  is  rc])r('sciitc(I  1)\-  tlic  ( 'roinci-  I'lay,  the  second  hy  the 
ijreat  chalky  ])OAvhhM-  clay,  the  fluid  1)\  tlic  piirphi  clay  of  Iloltlorness,  am] 
the  fourth  l)y  the  Hessle  Clay.  In  Hcotlaiid,  France,  GeiTQauy  and  Scan- 
dinavia the  series  of  de})osits  are  less  perfect. 

Archibald  Geikie,  having  before  him  the  same  evidence,  recognizes  for 
England  and  Europe  generally  only  two  glacial  epochs,  the  glaciers  of  the 
second  T)eing  smaller  than  those  of  the  first  and  to  a  greater  extent  local. 
He  recognizes  also  the  iiiterru})tion  of  the  first  l)y  warmer  epochs,  re})re- 
seuted  by  interglacial  beds,  but  these  do  not  with  liini  constitute  an  element 
of  the  })rimary  classification.' 

In  northeastern  Iowa,  the  stratigraphy  of  the  superficial  formations 
has  ])een  studied  by  McGee,  avIio  deduces  the  following  history.  First,  the 
extension  of  the  northern  ice  over  the  region;  second,  its  withdrawal  "and 
a  period  of  nnldclimatal  conditions  which  nnist  have  been  of  innnen.se  dura- 
tion"; third,  a  second  and  last  great  glacial  advance;  fourth,  a  tliird  slight 
advance  of  the  ice,  of  which  indirect  results  only  Avere  observed  in  north- 
eastern Iowa."  The  formation  representing  the  long  interglacial  period  is 
a  "forest  bed",  a  ligneous  stratum  separating  two  deposits  of  till.  An  equiv- 
alent forest  bed  in  Ohio  has  been  interpreted  by  Newberry  in  the  same 
way.^ 

Upham,  whose  most  important  personal  studies  were  in  Minnesota  and 
adjacent  parts  of  Dakota  and  Manitoba,  distinguishes  "two  principal  glacial 
epochs  .  .  .  each  sul)divided  by  times  of  extensive  recession  and  readvance 
of  the  ice  .  .  .  A  long  period  intervened,"  during  whicli  the  ice  proliably 
retreated  as  far  as  Hudson  Bay.* 

Chamberlin,  whose  studies  of  American  glacial  ])henomena  have  been 
exceptionally  comprehensive,  gives  the  following  generalized  talilc  of  Pleis- 
tocene fonnations  and  events.* 

'Text  Book  of  Giiology,  1S82,  pp.  83.->-8;i3,  896. 

-On  thu  complete  series  of  Su])erlici;il  Formations  in  Northeastern  Iowa.  Hy  W.  ,J.  MeGee.  Proc. 
.\ni.  Ass.  Adv.  Sci.  vol.  27,  1879,  pp.  198--,':il. 

•'Tlie  Drift  Deposits  of  Indiana,  l),v  J.  S.  Newberry;  in  lllli  .\nn.  Kep.  (ieol.  and  Nat.  Jlist.  of 
Indiana,  by  .John  Collett,  1884,  p.  90. 

■•Warren  Upluuii;  Proc.  Am.  Ass.  Adv.  Sei.  vol.  :52.  1884,  pp.  SJ-J,  223.  See  also  Geol.  and  Xal. 
Hist.  Snrvey  of  Minnesota,  vol.  1  of  Final  Kept.,  1884,  pp.  40(i,  481,  .'■)80. 

*Tlie  Driftless  Area  of  the  Upper  Mississippi.  By  T.  C.  Chamberlin  and  R.  D.  Salisbury.  Sixth 
Ann.  Kept.  U.  S.  Geol.  Survey,  188".,  p.  212. 


AMERICAN  OPINIONS  OF  BIPARTITION. 


273 


Epochs. 

Sabepochs  or  Episodes. 

Attendant  or  characteristic  phenomena. 

Not  yet  sati-'^factorily  dis- 
tinguished from  the  Plio- 
cene. 
First  aubepoch  or  epj.'iode. 

^  Interglacial    subepoch    or 
episode  of  doglaclation. 
Sucood  subepoch  urepisode  - 

Drift  sheet  with  attenuited  border;  absence  or 
nieagerness  of  coarse  ultra-marKiual  drainage 
drift. 

Decomposition,  oxidation,  ferrugination.  vegetal 
accumulation. 

Drift  sheet  with  attenuated  border;  loess  contem- 
poraneous with  closing  stage. 

Elevation  of  the  upper  Mississippi  region  1.000± 
feet.  Erosion  of  old  dritt,  decomposition,  oxida- 
ti'tn,  ferrugination,  vegetal  accuniulatious. 

Till  sheet  bordered  by  the  Kettle  or  Altamont 
moraine. 

Vegetal  deposits. 

Till  sheet  bordered  by  the  Gary  moraine. 

Till  bordered  by  the  Antelope  moraine. 

Marked  by  teiminal  uiuraines  ot  undetermined 
importance. 

Marine  deposition  in  the  Champlain  and  Saiot 
Lawrence  valleys  and  on  Atlantic  border;  lacus- 
trine deposits  about  the  Great  Lakes. 

Marked  by  fluvial  excavation,  uotahly  of  the  flood 
plains  of  second  glacial  epoch. 

n.  Earlier  j;lacial  epnch 

III.  Chief  interglacial  epoch 

IV.  Later  glacial  epoch 

First  episode  or  subepoch  -  - 

Episode  of  deslaciatiou  .. 
■^  .Second  8t;ign  or  suhepoch  . 

Episode  of  deglaciation 

1  Third  episode 

VI.  Terrace  epocli 

According  to  Newberry  "  there  were  two  maxima  of  cold  separated 
by  a  long  interval  in  wliich  the  climate  was  ameliorated";  but  this  climate 
was  still  cool,  and  the  ice  probably  did  not  retreat  far  beyond  the  Great 
Lakes/ 

While  the  conclusions  of  McGee,  Upham,  Chamberlin  and  Newberry 
are  based  jjrimarily  on  studies  in  contiguous  districts,  include  to  a  large 
extent  the  same  phenomena,  and  agree  in  recognizing  two  maxima  of  cold, 
those  of  Chamberlin  and  Upham  are  the  only  ones  in  complete  accord. 
Newberry  differs  from  the  others  in  that  he  regards  the  inter-maximum  ics 
retreat  as  relatively  small.  Chamberlin  and  McGee,  agreeing  that  glacia- 
tion  was  interrupted  by  a  long  epoch  of  warmth,  and  that  it  was  also  varied 
by  episodes  of  local  or  temporary  retreat  of  the  ice  sheet,  differ  in  their  ref- 
erence of  an  important  bed  of  till,  and  hence  draw  differently  their  lines  of 
primary  classification.  McGee's  interglacial  period  "of  immense  duration" 
is  Chamberlin's  "interglacial  subepoch  or  episode  of  deglaciation ",  and 
McGee's  "  second  and  last  great  glacial  advance  "  is  Chamberlin's  "  second 
subepoch  "  of  the  "  earlier  glacial  epoch."^ 

By  later  investigation  McGee  finds  evidence  as  to  epochs  of  cold  in  the 
]ilienomena  of  the  deposits  and  erosions  of  the  Atlantic  border  south  of  the 
Drift.     From  this  investigation  he  concludes  that  the  Pleistocene  included 

'Nortb  America  in  the  Ice  Period.     By  John  S.  Newberry.     Pop.  Sci.  Monthly,  vol.  30,  1886,  p.  9. 
^See  McGee  in  Am.  Jour.  Sci.  :{(1  series,  vol.  35,  1888,  pp.  458-461. 
MON  I 18 


274  LAKE  BONNEVILLE. 

two  and  only  two  great  epochs  of  cold ;  that  tliese  epochs  were  separated 
by  an  interval  three,  five,  or  ten  times  as  long  as  the  i)ost-glacial  interval ; 
and  that  the  earlier  cold  endm-ed  mnch  the  longer  and  was  the  less  intense.' 
These  inferences  are  harmonions  either  with  Chanil)erlin's  conclnsions  or 
with  his  own  results  in  Iowa,  taken  separately,  and  they  correspond  closely 
with  my  reading  of  Bonneville  history;  by  substituting  the  terms  "wet" 
and  "lacustral"  for  "cold"  and  "glacial,"  the  Bonneville  story  can  be 
summed  up  in  tlie  same  words  as  McGee's  story  of  the  Atlantic  border. 

Wright  early  advocated  the  unity  of  the  period  of  glaciation  in  America 
and  still  adheres  to  tliat  view.  In  a  recent  publication  he  states  that  "  most 
of  the  facts  adduced  to  support  the  theory  of  distiiict  epochs  are  cajiable  of 
explanation  on  the  theory  of  but  one  epoch  with  the  natural  oscillations 
accompanying  the  retreat  of  so  vast  an  ice-front."^ 

The  latest  word  on  the  subject  is  from  James  Geikie,'  whose  digest  of 
results  obtained  by  geologists  of  continental  Europe  comes  to  hand  \\hile 
these  pages  are  in  proof  The  plain  of  northern  Germany  was  twice  over- 
run by  the  Scandinavian  ice  sheet,  and  experienced  a  temperate  climate  in 
the  interval.  Students  of  Alpine  di-ift  recognize  more  than  two  epochs  of 
glacier  extension,  and  it  is  possible  that  the  interglacial  deposits  of  the 
northern  plain  do  not  all  belong  to  the  same  interglacial  epoch. 

From  this  summary  of  opinions  it  aj)pears  that  the  relatively  simj)le 
conception  of  Pleistocene  history  which  belonged  to  the  early  stages  of  its 
investigation  has  been  generally  replaced  b}-  the  \"iew  that  its  climate  was 
characterized  by  great  oscillations.  This  result  has  been  reached  separately 
and  through  independent  methods  by  European  and  American  students. 
l)ut  while  the  fact  of  oscillation  is  widely  accepted  for  each  continent,  the 
progress  of  investigation  seems  not  yet  to  have  rendered  the  two  histories  so 
definite  that  the  question  of  their  similarity  and  svnclu'onism  can  profitably 
be  discussed.  Whatever  confidence  we  may  have  that  the  Plei-stocene  gla- 
ciation was  a  recurrent  phenomenon,  it  must  be  admitted  that  ])arallelism 
of  recurrence  remains  to  be  proven.     It  follows  that,  for  the  present  at  least, 

'  Am.  Joiir.  Sci.  3d  series,  vol.  35,  la-'H,  p.  403. 

■^Tho  Ice  Age  in  North  America.     By  G.  Froilerick  Wright.     New  York,  l!J89,  p.  500. 

'Address  to  the  Geological  section  of  the  B.  A.  A.  S.,  September,  1889. 


GENETIC  CORRELATION  OF  LAKES  AND  GLACIERS.  275 

parallelism  of  recurrence  can  not  with  confidence  be  ajipealed  to  in  tlie 
correlation  of  the  lacustral  history  with  the  glacial  history. 

Genetic  correiation—Tlic  fourtli  point  of  analogy  is  genetic.  It  is  generally 
believed  that  any  climatic  change  competent  to  restore  the  g'laciers  of  Cali- 
fornia and  Utah  would  likewise  restore  the  ancient  lakes  of  the  Great  Basin. 
From  this  belief  there  has  been  no  dissent,  and  it  is  certainly  plausible ; 
but  it  must  nevertheless  be  admitted  that  meteorology  in  its  present  stage 
affords  it  no  satisfactory  basis.  Tlie  general  subject  of  climate  is  highly 
complex,  and  Its  laws  are  not  so  well  understood  that  the  results  of  new 
combinations  of  conditions  can  be  foretold. 

The  size  of  lakes  and  the  size  of  glaciers  are  determined  by  three 
processes : 

A.  Precipitation  of  rain  and  snow. 

B.  Evaporation  of  water,  snow  and  ice. 

C.  Melting  of  snow  and  ice. 

The  essential  elements  of  local  climate  upon  which  the  local  I'ates  of 
these  three  processes  depend  are  at  least  four  in  number,  and  may  conven- 
iently be  indicated  under  five  heads  : 

(rt)  The  temperature  of  the  air. 

(b)  The  vapor  tension  or  vapor  content  of  the  air,  or  the  temperature 
of  the  dew  point.' 

(c)  The  general  velocity  of  the  wind. 

(d)  The  degree  of  cylonic  activity  ;  and  finally, 

(e)  The  variation  of  these,  and  the  distribution  of  their  variations 
through  the  year. 

'  For  the  iintechnical  reader,  these  terms  may  stand  in  need  of  deliuition.  The  invisible  moist- 
ure contained  in  the  air  is  called  aqueous  vapor,  and  has  the  properties  of  .a  gas.  By  virtue  of  its 
elasticity  it  exerts  a  certain  tension,  and  this  tension  is  the  measure  of  the  amount  pretsent  at  any 
point.  Vapor  tension  and  ra^jor  coH(eH(  are  therefore  synonymous.  The  amount  of  moisture  .air  will 
hold  without  condensation  is  limited,  and  the  limiting  amount  varies  with  temperature.  For  each 
temperature  there  is  a  maximum  vapor  tension  known  as  the  tension  of  saturation ;  for  each  vapor 
tension  there  is  a  minimum  temperature  known  as  the  drw  point.  The  temperature  of  the  dew  point 
at  any  place  and  time  is  thus  an  index  of  the  existing  vapor  tension.  Relative  humidity  is  the  ratio  of 
the  actual  vapor  tension  to  the  saturation  tension  corresponding  to  the  actual  temperature ;  it  is  the 
humidity  reckoned  in  terms  of  saturation  as  unity. 


276  LAKE  BONNEVILLE. 

The  move  general  terrestrial  conditions  wliich  immediately  determine 
these  local  elements  may  likewise  be  enumerated  under  five  heads.    They  are : 

(1)  The  latitude  of  the  locality. 

(2)  Tlie  altitude  of  the  locality,  and  the  system  of  altitudes  in  its 
vicinity. 

(3)  The  distribution  of  land  and  water  in  a  very  large  district  includ- 
ing the  locality. 

(4)  The  system  of  currents  in  oceans  within  this  district  (a  function 
of  1  and  3). 

(.O)  The  wind  dfrection  (a  function  of  1,  3,  and  4). 

Directly  or  indirectly,  each  of  these  five  conditions  affects  each  of  thfe 
five  elements  of  local  climate,  so  that  there  is  a  most  intricate  plexus  of  cause 
and  effect.  In  a  qiialitative  way  much  is  known  of  the  nature  of  these 
relations,  but  quantitatively  very  little  is  known.  It  i.s  perhaps  fair  to  say 
that  the  relations  of  temperature  and  humidity  to  latitude  and  altitude  are 
the  only  ones  whose  numerical  laws  have  been  successfully  investigated, 
either  theoretically  or  empirically.  Gradually  the  various  climates  of  the 
earth  are  being  explained  and  referred  to  their  proximate  causes;  but  the 
time  has  not  come  when  the  meteorologist  can  trace  out  the  quantitative 
relations,  or  even  in  any  fullness  the  qualitative  relations,  of  a  specific 
hypothetic  change  in  one  of  the  conditions  of  climate.  Such  a  pr(il)lcni 
as  the  distribution  of  climates  if  the  direction  of  terrestrial  rotation  wvre 
reversed  can  at  present  be  solved  only  in  a  very  rude  way. 

In  the  presence  of  such  complexity,  theories  are  nec^ssaril}-  based  upon 
partial  views,  and  the  hypothesis  or  opinion  that  the  magnitudes  of  enclosed 
lakes  and  of  glaciers  are  similarly  aftected  by  climatic  changes  ajjpi'ars  to 
depend  upon  such  a  partial  view.  This  was  certainly  tlu'  case  when  I 
advanced  the  opinion  in  an  earlier  paper. 

Let  us  assume  that  in  the  region  of  the  Great  Basin  and  tlic  surround- 
ing mountains  the  aqueous  vapor,  the  wind  v(■lo(•it^•,  the  cvclonir  activity, 
and  the  annual  oscillations  of  these  climatic  elements  remain  constant,  while 
tlie  tenq)erature  alone  undergoes  variation.  The  cause  of  the  tenqierature 
change  lies  of  course  in  a  modification  of  some  climatic  condition,  and  such 
modification  would  necessarily  have  its  effect  upon  vapor,  wind  velocity, 


EFFECT  OF  LOCAL  TEMPERATURE  CHANGE.  277 

etc.,  but  this  effect  is  by  the  present  assumption  ignored.  Conceive,  first, 
a  hiwering  of  local  temperature.  The  vapor  tension  remaining  the  same, 
the  relative  humidity  of  the  air  would  be  greater  than  at  present;  and 
cyclonic  activity  remaining  the  same,  the  increase  in  relative  humidity  would 
cause  increase  in  precipitation  of  rain  or  snow.  The  wind  velocity  remain- 
ing the  same,  the  lowering  of  temperature  would  retard  evaporation,  a 
smaller  share  of  the  moisture  precipitated  on  the  land  surfaces  of  the  Great 
Basin  would  return  to  the  air,  and  a  larger  share  would  gather  in  streams 
and  flow  to  the  lakes.  Evaporation  from  the  lake  surfaces  would  be  sloAver, 
and  the  lakes,  with  increased  supply  and  diminished  dissipation,  would  grow 
deeper  and  broader,  just  as  they  did  of  old.  In  the  mountains  the  lower- 
ing of  temperature  would  increase  the  length  of  the  season  during  which 
precipitation  takes  the  solid  form,  and  a  greater  proportion  of  the  total 
precipitation  would  be  in  snow.  The  increased  relative  humidity  of  the 
atmosphere  would  occasion  a  greater  total  precipitation,  and  the  winter's 
accumulation  of  snow  would  thus  be  doubly  augmented.  The  same  cause 
would  diminish  the  annual  evaporation  of  snow,  and  the  shorter  and  cooler 
summer  would  have  less  melting  power.  In  every  way  the  accumulation 
of  snow  and  ice  would  be  promoted  and  its  dissipation  checked.  The  small 
glaciers  which  hang  about  some  of  the  highest  crests  would  wax  in  size  and 
others  would  reoccupy  the  empty  cii'ques,  until  finally  a  broad  mantle  of 
snow  and  ice  would  cover  the  high  district  of  the  Sierra,  and  ice  streams 
would  flow  to  the  valleys  on  either  side,  just  as  of  old. 

Conceive  now  a  rise  of  local  temj^jerature.  Tlie  relative  humidity  of 
the  air  would  be  less  than  at  present;  the  precipitation  in  rain  and  snow 
would  be  less;  the  evaporation  would  be  more  rapid,  antl  a  smaller  share 
of  the  diminished  precipitation  would  gather  in  streams  and  flow  to.  the 
lakes.  The  lakes,  with  decreased  supply  and  increased  dissipation,  would 
grow  shallower  and  smaller.  In  the  mountains  the  winter  would  be  shorter, 
and  a  smaller  share  of  the  diminished  precipitation  would  take  the  form  of 
snow.  The  evaporation  of  snow  would  be  more  rapid,  and  the  longer  and 
warmer  summer  would  have  greater  melting  power.  The  supply  of  snow 
wovild  be  diminished  and  its  dissipation  would  be  promoted.  The  existing 
small  glaciers  would  disappear. 


278  LAKE  BONNEVILLE. 

Let  us  now  assume  that  in  the  same  region  the  temperature,  wind 
velocity,  etc.,  remain  constant,  while  the  vapor  tension  alone  undergoes 
variation.  Conceive,  first,  an  increase  of  local  vapor  tension.  The  tem- 
perature remaining  the  same,  the  relative  humidity  of  the  air  is  increased, 
and  this  increase  in  relative  humidity  causes  increase  in  precipitation  of  rnin 
and  snow.  It  induces  also  a  slower  evaporation.  The  supply  of  water  to 
the  lakes  is  increased,  their  superfcial  waste  is  diminished,  and  they  grow 
in  size.  On  the  mountains  the  snowfall  is  increased,  though  its  period  remains 
the  same.  The  dissipation  of  snow  by  evaporation  is  less,  the  melting  of 
snow  l)y  direct  insolation  is  sensibly  unchanged,  l)ut  its  melting  by  sunmier 
rains  is  accelerated.  In  the  region  of  the  Sierra  glaciers  the  sunnner  pre- 
cipitation is  so  small  as  compared  with  the  winter  that  this  last  factor  can 
not  be  important;  and  we  need  not  doubt  that  accumulation  of  snow  would 
exceed  dissipation,  causing  an  extension  of  the  glaciers.  Conceive  now  a 
diminution  of  vapor  tension.  The  preceding  relations  are  evidently  reversed. 
The  lakes  of  the  Great  Basin  receive  less  from  the  streams  and  part  witli 
more  to  the  air,  and  therefore  shrink.  The  glaciers  of  the  Sierra  receive 
less  snow,  lose  more  by  evaporation  and  lose  slightly  less  l)y  melting,  and 
they  will  therefore  shrink. 

It  thus  appears  that  a  local  change  in  temperature  alone  or  a  local 
change  in  moisture  alone  would  cause  the  lakes  of  the  Great  Basin  and  the 
glaciers  of  the  Sierra  simultaneously  to  enlarge  or  simultaneously  to  con- 
tract. But  wdien  Ave  consider  their  concurrent  change,  no  such  definite 
conclusion  is  possible.  If  rise  of  temperature  is  accompanied  bA-  diminu- 
tion of  vapor  tension,  there  will  be  a  common  shrinkage  of  lakes  and 
glaciers,  for  these  climatic  changes  have  the  same  tendency.  Similarl\-,  if 
fall  of  temperature  is  accompanied  by  increase  of  vapor  tension,  lakes  and 
glaciers  will  grow;  but  a  rise  of  temperatin-e  and  an  increase  of  vapor,  or 
a  fall  of  temperature  and  a  decrease  of  vapor,  will  have  antagonistic  efiects 
upon  both  lakes  and  glaciers,  and  the  nature  of  their  resultant  can  not  be 
determined  without  quantitative  data.  We  need  greatly  to  extend  our 
knowledge,  not  only  of  climatic  laws,  but  of  the  climate  and  phvsical 
geogra})hy  of  the  Great  Basin,  to  enable  us  to  determine  wliar  increase  of 
vapor  tension  is  adequate  to  neutralize  the  effect  of  one  degree's  rise  of 


^ 


EFFECT  OP  LOCAL  HUMIDITY  CHANGE.  279 

temperature  upon  the  size  of  the  hikes;  and  we  need  in  addition  greatly  to 
extend  our  knowledge  of  the  climate  of  the  Sierra  Nevada  to  enable  us  to 
determine  what  increase  of  vapor  tension  will  neutralize  the  effect  of  one 
degree's  rise  of  temperature  upon  the  size  of  the  glaciers.  It  is  only  in 
the  case  that  these  two  increments  of  vapor  tension  are  equal,  that  increase 
of  lakes  and  increase  of  glaciers  will  be  invariably  coordinate.  If  they 
are  unequal,  then  it  is  possible  to  assume  simultaneous  changes  of  tempera- 
ture and  vapor  tension  under  whose  influence  the  lakes  will  expand,  while 
the  glaciers  shrink,  and  vice  versa. 

But  this  view  of  the  case  is  still  only  partial.  Any  change  in  the  alti- 
tude of  the  district,  in  the  position  of  the  adjacent  coast  of  the  Pacific,  in 
the  nature  of  the  currents  of  the  North  Pacific,  or  in  the  direction  of  the 
prevailing  wind,  would  not  only  modify  the  temperature  and  humidity  of 
the  district  under  consideration,  but  would  affect  the  wind  velocity,  the 
cyclonic  activity,  and  the  cycle  of  annual  climatic  change.  A  variation  of 
wind  velocity  Avould  make  itself  felt  in  the  rate  of  dissipation  of  lakes  and 
glaciers;  a  variation  in  cyclonic  activity  would  manifest  itself  in  the  supply 
of  Avater  and  .snow  to  lakes  and  glaciers;  and  a  variation  in  the  anmial 
cycle  of  climate  might  affect  lakes  and  glaciers  not  only  miequally  but 
diversely. 

Too  little  is  known  of  these  last  mentioned  influences  to  warrant  any 
attempt  to  discuss  them  here.  For  this  reason,  and  for  this  ouh',  they  will 
be  ignored  in  the  following  paragraphs;  but  it  is  understood  that  the  con- 
siderations about  to  be  advanced  are  subject  to  whatever  modification  -^ev- 
tains  to  the  omitted  factors.  Restricting  attention  to  the  two  elements  of 
local  climate,  temperature  and  vapor  tension,  we  will  now  endeavor  to 
ascertain  how  the  lakes  and  glaciers  of  the  district  would  be  affected  through 
them  b}'  various  postulated  changes  of  climatic  conditions. 

Let  us  inquire,  first,  what  will  result  from  a  general  change  of  altitude, 
or  more  specifically,  from  a  bodily  uplift  of  the  entire  district,  including 
the  Great  Basin  and  the  adjacent  mountains.  It  is  Avell  known  that  both 
temperature  and  A-apor  tension  are  inverse  functions  of  altitude;  the  tem- 
perature of  the  district  will  be  lowered  by  the  uplift,  and  the  moisture 
normal  to  the  new  altitude  will  be  less.     The  atniosphere  covering-  this 


280  LAKE  BONNEVILLE. 

distru't  is  part  of  a  great  eastward-tending  current  which  derives  its  moist- 
ure from  the  North  Pacific  Ocean.  The  hypothetic  change  of  altitude  will 
not  affect  its  humidity  where  it  enters  the  district.  Its  vapor  tension  can 
be  reduced  to  the  noniial  only  by  precipitation,  and  if  not  thus  reduced, 
there  will  l)e  an  increase  of  relative  humidity,  owing  to  the  lowering  of 
temperature.  We  shall  have,  then,  for  the  district,  either  an  increase  of 
precipitation  or  an  increase  of  relative  humidity.  The  former  woidd  aug- 
ment the  supply  of  Avater  for  the  lakes  and  of  snow  for  the  glaciers;  the 
latter  woidd  retard  evaporation  and  thus  diminish  the  waste  of  water  and 
ice.  The  loAvering  of  temperature  likewise  will  not  only  retard  evaporation, 
but  will  retard  melting,  and  will  extend  the  season  in  which  precipitation 
takes  the  form  of  snow.  Thus,  in  every  way,  the  growth  of  lakes  and 
glaciers  will  be  favored.  Conversely,  a  general  depression  of  the  district 
will  diminish  lakes  and  glaciers. 

Let  us  inquire,  in  the  second  place,  how  the  climate  will  be  affected  by 
changing  the  distribution  of  land  and  water.  Evidently,  the  number  of 
different  changes  which  might  be  postulated  is  unlimited,  but  there  is  one 
particular  change  to  which  the  district  is  peculiarly  sensitive,  and  which 
may  stand  for  a  large  class.  This  change  is  an  eastward  or  Avestward  move- 
ment of  the  coast  line  of  California,  so  as  to  diminish  or  increase  the  belt 
of  land  between  the  Sierra  Nevada  and  the  ocean.  Let  us  postulate  a  west- 
ward movement,  or  an  increase  of  the  land.  The  general  movement  of  the 
atmosphere  in  this  region  is  from  the  ocean  to  the  land,  and  the  moisture 
gathered  from  the  surface  of  the  ocean  is  the  store  whence  all  the  precipita- 
tion of  the  land  is  derived.  The  addition  of  a  belt  of  land  will  inci-ease  the 
area  of  uncompensated  precipitation,  and  will  thus  duninish  the  general 
vapor  tension  of  the  atmosphere  of  the  district.  It  has  been  pointed  out  by 
Button,^  that  the  portion  of  the  ocean  under  consideration  has  a  temjierature 
lower  than  the  normal  for  the  latitude,  so  that  the  air  current  grows  warmer 
in  passing  over  the  land.  The  intervention  of  an  additional  belt  of  land 
will  add  its  quota  of  heat  to  the  air,  and  thus  render  the  general  tempera- 
ture of  the  district  higher.     An  addition  to  the  coast  will  therefore  induce 

'On  the  cause  of  the  arid  climate  of  the  western  portion  of  the  United  States,  by  Capt.  C.  E. 
Uutton,  Am.  Jour.  Sci.,  :!d  scries,  vol.22,  p.  247.     See  also,  Haun's  Handbuch  der Klimatologie,  p.  13(>. 


EFFECT  OF  HYPOTHETIC  OCEANIC  CHANGES.  281 

a  diminution  of  vapor  and  a  rise  of  temperature,  and  these  changes,  as  we 
have  .seen,  are  competent  to  diminish  lakes  and  glaciers.  The  reverse  effects 
\\  ill  of  course  be  wrought  by  a  dimiiuition  of  the  coast  area. 

Tliird,  let  us  endeavor  to  see  how  our  district  would  be  affected  by  a 
moditication  of  ocean  currents,  The  influence  of  such  currents  u^ion  cli- 
mates is  exerted  through  their  temperature;  and  we  will  postulate  a  rise  in 
the  temperature  of  the  current  which  follows  the  coast  of  California  from 
north  to  south.  A  warmer  ocean  will  give  a  higher  temperatvxre  to  the  land- 
ward-flowing air,  and  at  the  same  time  impart  to  that  air  a  greater  load  of 
aqueous  vapor.  Since  the  oceanic  district  in  question  is  now  cooler  than 
the  land  district  whose  atmosphere  it  tempers,  a  warming  of  the  ocean  will 
tend  to  diminish  the  contrast  of  temperatures.  The  warming  of  the  air 
during  its  landward  progress  will  therefore  be  less,  and  there  will  be  a 
tendency  towards  a  higher  relative  humidity.  Precipitation  will  thus  be 
promoted.  Evaporation  will  be  favored  by  the  higher  temperature,  but 
opposed  by  the  higher  relative  humidity;  and  it  is  not  easy  to  see  which 
tendency  will  prevail.  The  melting  of  snow  and  ice  will  be  promoted  both 
by  the  higher  temperature  and  by  the  greater  length  of  the  summer,  while 
the  winter,  or  the  season  in  which  precipitation  takes  the  form  of  snow,  will 
be  shortened.  So  long  as  only  a  small  change  is  considered,  the  merely 
qualitative  statement  does  not  clearly  show  whether  the  increased  rate  of 
snowfall  will  he  more  or  less  than  compensated  by  the  increased  rate  of 
melting;  and  the  uncertainty  in  regard  to  evaporation  leaves  us  in  doubt 
whether  the  lakes  will  swell  or  shrink. 

If,  however,  we  pass  to  an  extreme  case,  there  is  no  room  for  doubt. 
A  great  increase  of  oceanic  temperature,  say  ten  or  twenty  Fahreidieit 
degrees,  would  reverse  the  contrast  of  temperature  between  land  and  shore. 
The  eastward-flowing  air,  instead  of  being  warmed  by  the  land,  would  be 
cooled;  and  the  resulting  pi-ecipitation  would  far  surpass  any  possible  in- 
crease of  evaporation.  The  Great  Basin  would  become  a  basin  of  great 
lakes.  The  same  temperature  change  would  so  abridge  the  winter  season 
in  the  mountains,  and  so  enhance  the  melting  power  of  the  sunuuer,  that  no 
glacier  could  possibly  survive.     The  converse  follows. 


282  LAKE  BONNEVILLE. 

Finall|)',  let  us  ask  what  will  result  from  a  change  iu  the  direction  of 
the  generixl  air  current.  This  direction  belongs  to  the  great  syst^jin  of 
atmospheric  circulation,  and  a  large  change  is  practically  out  of  the  ques- 
tion. We  are  at  liberty,  however,  to  assume  small  changes,  based  upon 
local  conditions;  and  -we  A\ill  |)ostulate  that  the  wind  becomes  more  south- 
erly. With  such  a  course,  it  will  derive  its  temperature  and  moisture  from 
a  portion  of  the  Pacific  Ocean  warmer  than  that  now  traversed  by  it;  and 
the  ])rincipal  effects  in  the  mountain  district  under  consideration  will  be 
identical  with  those  deduced  in  the  last  paragraph,  as  resulting  from  a 
warmer  ocean.  Minor  effects  will  be  conditioned  by  the  configuration  of 
the  belt  of  land  traversed  by  the  wind  before  reaching  the  interior  district, 
and  the  distribution  of  climate  within  the  district  will  be  modified;  but  the 
probable  importance  of  these  considerations  is  not  sufficient  to  warrant 
their  discussion. 

It  appears,  then,  that  lakes  and  glaciers  would  simultaneously  increase 
if  the  district  as  a  whole  Avere  to  be  uplifted,  or  if  the  Pacific  Ocean  were 
to  encroach  upon  the  California  coast;  and  the  conclusion  is  less  confidently 
reached  that  the  lakes  of  the  Great  Basin  would  increase,  and  the  glaciers 
of  the  Sierra  Nevada  decrease,  if  the  North  Pacific  Ocean  Avere  wanner,  or 
if  the  coastward  Avinds  traA'ersed  a  Avarmer  tract.  But  the  subject  is  by  no 
means  exhausted.  We  mig-lit  consider  the  various  combinations  of  these 
four  postulated  changes  of  condition,  or,  going  beyond  them,  Ave  might  turn 
our  attention  to  those  more  remote  causes  of  change  to  Avliirh  theories  liaA-e 
appealed  in  explanation  of  Pleistocene  glaciation.  Whether  Ave  attempted 
to  trace  out  the  consequences  of  far-reaching  geographic  changes,  of  varia- 
tions in  the  eccentricity  of  the  earth's  orbit,  or  of  the  terre.striid  \\  andcring 
of  the  earth's  axis  of  rotation,  Ave  should  equally  find  ourseh-es  iuA-olved  in 
a  maze  of  complexity,  and  ultimately  brought  face  to  face  Avith  the  imjier- 
fection  of  the  science  of  meteorology. 

RevieAving  the  innnediately  preceding  discussion,  avc  see  that  tlu'  partial 
view  Avhich  takes  account  of  temperature  onh',  or  of  a(pie(ius  \apor  only, 
results  in  a  definite  conclusion.  The  Ijmadcr  but  still  partial  aIcw  wliicli 
takes  account  of  temperature  aud  iupicdus  Aapor  conjointh-,  l)ut  neglects 
other  climatic  elements,  leads  to  no  definite  conclusion.     Certain  climatic 


ARGUMENT  FROM  CLIMATIC  CHRONOLOGY  SUMMED.  283 

conditions,  manifesting  themselves  through  temperatm-e  and  liumidity, 
affect  hxkes  and  ghxciers  in  the  same  way,  while  other  climatic  conditions 
affect  them  in  opposite  ways. 

Reviewing-  the  entire  discussion  of  climatic  analogies,  we  are  forced  to 
the  conclusion  that  the  weight  of  the  analogic  argument  for  the  correlation 
of  lakes  and  glaciers  has  been  overestimated.  The  fact  remains  that  the 
lake  epoch  and  the  ice  epoch  belong-  to  the  same  short  division  of  geologic 
time;  so  does  the  further  fact  that  each  was  a  peculiar  episode,  interrupting 
a  distinct  and  ver}'  different  course  of  events.  These  two  facts  establish  a 
presimiption  in  favor  of  their  correlation,  but  this  presumption  gains  only 
moderate  support  from  the  parallel  bipartition  of  the  two  sets  of  phe- 
nomena, since  the  duality  of  the  glacial  epoch  is  not  generally  accepted; 
and  it  gains  no  su]:)port,  as  we  have  just  seen,  from  the  consideration  of  the 
climatic  conditions  affecting  the  lakes  and  glaciers  of  the  Great  Basin.  The 
correlation  of  the  phenomena  remains  as  a  working  li3-pothesis,  but  before 
it  can  regain  its  position  as  a  fully  credited  theory,  it  must  be  sustained  by 
new  arguments.  Fortunately,  the  data  for  its  further  discussion  have  been 
developed  by  tlie  geologic  researches  in  the  Great  Basin,  and  to  these  data 
we  shall  presently  proceed. 

THE  EFFECT  OF  A  CHANGE  IN   SOLAR  ENERGY. 

The  jjresent  place,  however,  is  more  convenient  than  any  other  for  the 
discussion  of  a  climatic  question  Avhose  answer  is  of  prime  im2)ortance  in 
the  interpretation  of  the  geologic  dat.t  just  referred  to.  The  question  is 
that  of  tlie  influence  of  a  general  change  of  temperature  upon  the  growth 
of  glaciers.  If  the  radiant  energy  of  the  sun  were  to  becf)me  greater  or 
less,  how  would  the  glaciers  of  the  earth  be  affected?  Would  an  increase 
in  the  accession  of  solar  heat,  or  would  a  decrease  in  its  accession,  cause 
the  present  glaciers  to  expand  and  new  areas  to  be  glaciated? 

It  is  a  familiar  fact  that  the  glaciers  of  the  present  day  are  restricted 
to  regions  where  the  temperature  is  low.  They  are  more  immerous  and  of 
greater  size  in  polar  regions,  and  there  oidy  do  they  reach  the  ocean;  in 
temperate  and  tropical  climates  they  occur  only^  on  high  mountains,  and 
their  lower  limit  varies  with  the  altitude,  being  highest  at  the  equator  and 
lowest  at  the  poles.     These  facts  of  distriljution  have  occasioned  the  preva- 


284  LAKE  BONNEVILLE. 

lent  (tpiiiiou  that  cold  is  the  ])riiuary  condition  of  g'laciation,  and  that  the 
climate  of  the  glacial  epoch  or  ejjochs  was  a  cold  climate.  If  it  were  believed 
by  all,  as  it  is  by  some,  that  Pleistocene  glaciation  was  produced  by  a  va- 
riation in  solar  radiation,  the  majority  would  conceive  that  variation  as  a 
diminution.  N(;vertheless,  there  are  not  wanting  iiivestigators  who  enter- 
tain the  opposite  view;  and  so  long  as  these  include  men  of  such  weight  as 
Frankland,'  Tyudall,-  GrolV  King,*  Whitney,^  and  Becker,"  the  majority 
should  at  least  refrain  from  dogmatic  assertion.  I  am  therefore  not  content, 
as  one  of  that  majority,  to  let  the  sul)ject  pass  with  a  mere  expression  of 
opinion. 

Generally  speaking,  the  vapor  tension  of  the  atmosphere  is  greatest  at 
sea  level,  and  it  decreases  rapidly  upward.  If  the  air  did  not  circulate, 
but  remained  stationary,  the  elastic  force  of  the  aqueous  vapor  would  cause 
it  to  be  diffused  ujiward,  and  the  product  of  evaporation  from  the  ocean 
surface  would  be  continuously  added  and  diffused  until  there  was  complete 
saturation  throughout.  The  theoretic  static  condition  of  the  atmo.sphere 
with  reference  to  moisture  is  one  of  saturation.  The  actual  condition  of 
imperfect  saturation  is  caused  by  the  vertical  movements  of  the  air.  These, 
in  accordance  with  well  known  laws,  produce  precipitation,  and  it  results 
that  the  vapor  tension  of  the  air  at  every  level  is,  generally  speaking,  con- 
siderably below  the  tension  of  saturation.  Strachey,  and  afterward  Ilann, 
by  studying  the  records  of  numerous  observations  at  different  altitudes  and 
in  diffei'ent  rescions,  have  deduced  the  g'eneral  law  of  vertical  distribution 
of  moisture.^     It  is,  that  the  relative  humidity  of  the  air  is  not  a  function 

'  Oa  the  physical  cause  of  the  Glacial  Epoch,  By  E.  Fraukland.  Philosophical  Magazine,  vol. 
27,  1864,  p.  321. 

^Tbe  Foruis  of  Water,  by  John  Tyiidall,  p.  151.  Also,  Heat  considered  as  a  Mode  of  Motion, 
Ch.ap.  VI. 

•'Climate  and  Time  in  their  Geological  Relations,  By  James  CroU,  New  York,  1875,  p.  79. 

■•The  Geological  Exploration  of  the  Fortieth  Parallel,  by  Clarence  King,  vol.  1,  p.  52.'i. 

'The  climatic  changes  of  later  geological  times,  by  J.  D.  Whitney,  Mem.  Mus.  Comp.,  Zool. 
vol.  7,  No.  2,  pp.  20.^-6,  ;i21,  '.iSS. 

<■  Temperature  and  glaciation,  by  G.  F.  Becker,  in  American  Journal  of  Science,  3d  series,  vol.  2G, 
pp.  167-175;  also  vol.  27,  pp.  473-476. 

'Ou  the  distribution  of  aqueous  vapor  in  the  upper  parts  of  the  atmosphere,  by  Lieut.  Col. 
Richard  Strachey,  F.  R.  S.,  Proceedings  Royal  Society  of  Loudon,  vol.  II,  1860,  p.  182. 

Ou  the  diminution  of  aqueous  vapor  with  increiisiug  altitude  in  the  atmosphere,  by  Dr.  Julius 
Hann,  Zoitschrift  Oest.  Met.  Gesell.,  lrJ74,  vol.  11,  p.  193.  (Cited  from  translation  by  Cleveland  Abbe 
in  Smithsonian  Report  for  1877,  p.  376.) 

Strachey  notes  that  the  conclusion  was  originally  reached  by  Ur.  Joseph  Hooker,  but  Hooker's 
inforeuce  was  based  ouly  upon  observations  in  the  Himalayas. 


EFFECT  OF  GENERAL  TEMPERATURE  CHANGE.  285 

of  altitude,  or,  in  other  words,  that  for  each  altitude  the  vapor  tension  bears 
the  same  relation  to  the  tension  of  satui-ation.  It  is  not  to  be  supposed  that 
this  law  is  ordinai'ily  illustrated  by  the  condition  of  a  local  atmospheric 
column  at  a  given  instant;  it  is  exemplified  only  through  the  comparison  of 
the  means  of  large  bodies  of  observations. 

Notwithstanding  the  empiric  nature  of  this  law,  it  is  possible  to  extend 
its  application  somewhat  beyond  the  existing  order  of  things;  for  it  is  evi- 
dent that  under  the  influence  of  atmospheric  circulation  the  humidity  of 
each  isothermal  and  isoliygral  stratum  of  the  atmosphere  is  determined  by 
the  humidify  of  the  stratum  beneath  it,  the  humidity  of  the  lowest  of  all 
being  determined  by  the  rate  of  evaporation  from  the  surface  of  the  ocean. 
A  universal  rise  in  the  temperature  of  tlie  atmosphere,  unless  it  was  suffi- 
cient to  materially  accelerate  the  circulation,  would  have  the  effect  merely 
of  raising  all  the  isothermal  strata  and  inserting  a  warmer  stratum  at  the 
base  of  the  series.  This,  by  virtue  of  its  higher  temperature,  would  accel- 
erate the  oceanic  evaporation,  and  thus  be  enabled  to  maintain  the  relative 
humidity  required  by  Strachey's  law.  Tliis  conclusion  implies  that  rates 
of  oceanic  evaporation  are  proportional  to  the  saturation  tensions  of  the  air 
at  the  surface  of  the  ocean,  so  long  as  the  relative  humidity  is  unchanged; 
a  proposition  readily  deducible  from  the  accepted  law  of  evaporation.^ 

In  stating  the  above  propositions,  it  has  not  been  possible  to  incorporate 
continuously  the  qualification  that  they  are  of  the  most  general  character 
and  ignore  the  extreme  variability  in  time  and  place  wliich  characterizes 
both  temperature  and  humidity.     Despite  this  qualification,  they  appear  to 

'  In  an  article  "On  the  depeniloiice  of  water  evaporation  ou  tlio  temperature  of  the  water  anil 
the  movement  of  the  air",  published  in  the  Repertoriiim  fur  Meteorologie,  St.  Petersburg,  l-^TT,  Article 
3,  p.  6,  Stelliug  deduces  and  applies  the  follovvinj;  formula: 

»  =  A(S  — 8)  -t-B  (S  — ?)"•> 
in  which  v  is  the  rate  of  evaporation,  S  is  the  saturation  vapor  tension  corresponding  to  the  tempera- 
ture of  the  evaporating  water,  .v  is  tlie  vapor  tension  of  the  air  in  contact  with  the  water,  ?«  is  the 
velocity  of  the  wind,  and  A  anil  15  are  constants.  Siuce  for  the  present  purpose  wo  may  ignore  local 
variations,  we  are  enabled  to  simplify  the  formula  by  regarding  the  contiguous  air  and  water  as  of 
the  same  temperature,  and  by  regarding  the  wind  as  coustaut.  With  this  modification  the  formula 
becomes: 

»  =  Constant  X  (S'  —  s),  or  r  =  Constant  x  S' (1  —  ^,)^ 

in  which  S'  is  the  saturation  tension  of  the  air.    The  fraction  |^  expresses  the  relative  humidity,  and 

since  this  is  by  postulate  constant,  we  have  t',  the  rate  of  evaporation,  a  simple  function  of  S',  the  sat- 
uration tension  of  the  air. 


286  LAKE  BONNEVILLE. 

me  to  warrant  the  following  corollary.  If  a  general  rise  should  take  place 
in  terrestrial  temi)erature,  affecting  all  local  temperatures  alike,  tlie  local 
moisture  condition  would  be  similarly  affected.  The  local  capacity  for 
moistun^  hcing  everywhere  greater,  the  local  vapor  tension  would  likewise 
be  greater,  but  the  relative  humidity  for  each  locality  would  remain  the 
same.  The  evaporation  not  only  from  the  ocean,  but  from  lakes  and  sur- 
faces of  ice  and  snow,  would  be  increased  in  the  ratio  of  the  increase  in  the 
local  saturation  tension. 

The  increase  in  capacit}'  for  moisture  for  every  unit  of  temi)erature 
change  is  not  in  precisely  the  same  ratio  at  all  temperatures,  being  somcwluit 
less  for  high  temperatures.  But  the  difference  is  so  small  that  no  material 
error  is  introduced  by  saying  that  the  evaporation  of  moisture  from  the 
entire  earth's  surface  is  proportional  to  the  saturation  tension  corresponding 
to  the  mean  temperature  of  the  surface.  Since  the  total  evaporation  is 
precisely  equal  to  the  total  precipitation,  it  follows  that  the  latter  likcAvise 
is  a  simi)le  function  of  the  saturation  tension,  and  the  distribution  of  temper- 
ature remaining  the  same,  the  local  precipitation  follows  the  same  hnv  of 
change  as  the  local  evaporation. 

Up  to  this  point  it  has  been  assumed  that  the  movements  of  the  atmos- 
phere in  direction  and  velocity  are  unaffected  by  a  general  change  of  tem- 
perature, and  it  now  remains  to  consider  the  validity  (^f  this  assumption. 
The  rate  of  evaporation  is  known  to  depend  in  part  on  the  velocity  of  the 
wind,  and  the  rate  of  precipitation  is  known  to  depend  in  part  upon  the 
amount  and  intensity  of  cyclonic  action.  We  will  give  first  consideration 
to  wind  velocity. 

The  mean  temperature  of  the  surface  of  the  earth,  reckone(l  from  the 
freezing  point  of  water,  is  about  +  IG°  (J.  The  absolute  zero  of  tempera- 
ture is  considered  to  he  —  273°  C,  so  that  the  mean  absolute  temperature 
of  the  earth's  surface  may  be  taken  as  289°.  If  the  constitution  of  the 
atmosphere  were  fixed,  it  is  prol^able  that  there  would  be  required,  to  in- 
crease of  temperature  of  the  earth's  surface  by  10°,  an  augmentation  of 
solar  heat  amounting  to  ^  or  i  of  the  present  amount.  In  fiict,  however,  the 
constitution  of  the  atmosphere  is  variable ;  at  higher  temperatures  it  con- 
tains a  larger  amount  of  aqueous  vapor,  and  its  power  to  absorb  and  retain 


GLACIATION  AND  SOLAR  EADIATION,  287 

heat  and  thus  acquire  temperature  is  reciprocally  augmeuted  l)y  aqueous 
vapor.  For  this  reason,  tlie  ratio  of  solar  radiation  to  lie  added  tor  1(P  rise 
of  temperature  is  something  less  than  ^^.  l^eing  unable  to  evaluate  this 
qualification,  we  shall  make  use  of  the  fraction  unchanged,  with  the  under- 
standing' that  it  is  too  larofe.  Owiuff  to  the  difference  in  attitude  of  tlie 
various  portions  of  the  earth  with  refei^enee  to  the  sun,  the  distribution  of 
solar  energy  is  unequal,  and  hence  arise  the  ])rincij)al  contrasts  of  tempera- 
ture on  the  earth's  surface.  These  contrasts  cause  the  atmospheric  circula- 
tion, by  means  of  which  a  partial  equalization  of  temperature  is  eff"ected. 
The  difference  between  the  solar  energy  received  in  high  latitudes  and  that 
received  in  low,  or  the  diff"erential  solar  energy,  is  the  force  manifested  in 
the  winds,  and  its  work  is  the  friction  of  the  circulation.  The  differential 
energy  is  directly  proportional  to  the  total  solar  energy.  The  law  of  aerial 
friction  is  not  known,  but  it  is  commonly  assumed  to  be  a  function  of  the 
square  of  the  velocity.  If  this  assumption  is  coi'rect,  then  the  square  of  the 
velocity  of  circulation  varies  as  the  solar  energy,  and  an  increment  of  ^  in 
solar  energy  will  produce  an  increment  of  i  in  velocity.  Considerations 
connected  with  the  conveyance  of  heat  through  the  circulation  of  moisture 
show  that  this  estimate  is  somewhat  too  large,  but  as  we  are  unable  to  give 
them  a  quantitative  expression,  we  pass  them  by.  The  formula  for  rate  of 
evaporation  given  by  Stelling  (see  note  to  page  285)  makes  that  rate  a 
direct  function  of  the  velocity  of  the  wind,  but  in  such  way  that  on  the 
average  the  rate  varies  only  about  ^  as  rapidly  as  the  wind.  The  ratio  of 
wind  acceleration  for  10°  rise  in  the  mean  temperature  of  the  earth's  surface 
being  less  than  j.'^,  the  ratio  by  which  evaporation  would  be  accelerated 
through  wind  velocity  by  the  same  rise  of  temperature  is  less  than  j^^.  The 
smallness  of  this  ratio  assures  us  that  the  acceleration  of  the  wind  may 
safely  be  disregarded  in  a  discussion  of  such  general  changes  of  tempera- 
-  ture  as  may  reasonably  be  postulated  to  account  for  Pleistocene  glaciation. 
The  conditions  under  which  cyclones  are  generated  are  comparatively 
obscure;  but  in  the  ultimate  analysis  they  are  necessarily  referred  to  differ- 
ential temperatures  created  by  the  sun.  It  is  probable,  therefore,  that,  like 
the  general  winds,  they  would  be  affected  little  by  a  general  rise  in  the 
temperature  of  the  atmosphere. 


288  LAKE  BONNEVILLE. 

It  is  to  be  noted  that  an  increase  in  wind  velocity,  by  increasing 
evaporation,  would  raise  the  relative  humidity,  and  thereby  increase  the 
preci})itation.  An  increase  in  cyclonism,  on  the  other  hand,  by  increasing 
precipitation,  would  decrease  the  relative  humidity,  and  thereby  increase 
evaporation.  The  conjoint  effect  upon  evaporation  and  precipitation  is 
therefore  cumulative,  while  the  effect  on  relative  humidity  is,  at  least  par- 
tially, compensatory. 

Finding  no  ground  for  important  ([ualificatron  on  account  of  varpng 
intensity  of  atmosjjheric  circulation,  we  return  to  the  original  deductions  as 
substantially  accurate:  First,  a  general  rise  of  terrestrial  temperature  will 
increase  evaporation,  general  and  local,  in  the  ratio  of  the  saturation  ten- 
sions corresponding  to  the  initial  and  final  temperatures.  Second,  it  will 
increase  precipitation,  general  and  local,  in  the  same  ratio. 

We  are  now  prepared  to  discuss  the  immediate  conditions  of  glacier 
growth,  and  will  first  consider  a  region  in  which  the  temperature  never 
rises  above  the  freezing  point.  In  such  a  region,  the  only  factors  affecting 
the  accumulation  of  snow  are  precipitation  and  evaporation.  If  the  former 
is  in  excess,  there  is  an  accumulation,  and  its  amount  is  measured  by  the 
difference  of  the  two  factors.  Since  each  of  these  factors  follows  the  same 
law  in  regard  to  temperature,  that  law  applies  also  to  their  arithmetical  dif- 
ference; and  a  change  in  the  mean  annual  temperature  will  affect  the  snow 
accumulation  in  the  same  ratio  that  it  affects  the  saturation  vapor  tension 
of  the  air.  If  the  temperature  rises  so  as  to  exceed  the  centigrade  zero 
during  a  portion  of  the  year,  the  annual  cvcle  of  climate  becomes  immedi- 
ately divided  into  two  portions,  which  it  will  l)e  convenient  to  call  winter 
and  sunnner.  Snow  accumulation,  then,  has  a  higher  rate,  by  reason  of  the 
higher  temperature,  but  tliis  higlicr  rate  is  restricted  to  a  sliorter  period. 
With  progressive  advance  of  amuinl  mean  tcmperatiu'i',  the  rate  of  snow 
accumulation  is  progressively  increased,  while  its  period  is  progressively 
shortened,  until  finally,  when  the  annual  temperature  c3-cle  falls  entirelv 
above  the  freezing  ])oint,  snow  accunudation  ceases  altogether. 

As  soon  as  the  temperatm-e  cycle  includes  sunnner,  a  thii-d  factor  is 
inti'oduced — melting.  Snow  is  melted  in  part  by  contact  with  warm  air,  in 
part  by  heat  radiation  from  the  lower  part  of  the  atmosjjhere,  in  part  by 


GLACIATION  AND  SOLAR  RADIATION. 


289 


direct  insolation,  in  part  by  the  heat  liberated  in  the  formation  of  dew,  and 
in  part  by  warm  rain.  Tlie  rate  of  melting  is  thns  a  complex  function  of 
the  temperature  of  the  air,  the  humidity  of  the  air,  the  clearness  of  the  sky, 
and  the  temperature  of  the  rain.  But  these  four  factors  are  so  i-elated 
among-  themselves  that  a  single  one,  the  temperature  of  the  air,  may  fairly 
Ije  regarded  as  the  measure  of  the  rate  of  melting.  The  temperatui-e  of 
the  lower  air  is  itself  conditioned  by  the  clearness  of  the  sky,  the  humidity 
of  the  air  is,  broadly  speaking,  conditioned  by  its  temperature,  and  the 
temperature  of  the  rain  is  conditioned  by  that  of  the  air.  The  total  annual 
loss  by  melting  depends  likewise  on  the  length  of  summer,  and  for  present 
purposes  its  measure  may  be  assumed  to  be  the  product  of  the  length  of 
summer  into  the  mean  temperature  of  summer,  exjjressed  in  centigrade 
degrees. 

For  the  purpose  of  bringing  together  the  conclusions  of  the  j^i'eceding 
paragraphs,  we  shall  now  resort  to  a  gi-apliic  method.  By  the  aid  of  a 
few  temporary  postulates,  the  law  of  snowfall  and  the  law  of  snow-melting 
may  each  be  given  the  form  of  a  curve,  and  the  relation  of  these  curves 
will  exhibit  the  law  of  n^vd  accumulation.  In  Fig.  35  the  line  X  X'  is  a 
scale  of  temperatures,  each  point  rep- 
resenting a  mean  annual  temperature 
of  a  particular  district.  The  tempera" 
^lu-es  are  reckoned  in  centigrade  de 
grees,  and  at  every  tenth  degree  a 
vertical  is  erected.  Vertical  distances 
represent  rates  of  snow  accumulation 
and  of  snow  melting.  For  the  con- 
struction of  the  curves,  three  postu- 
lates were  made.  First,  that  whatever 
the  mean  temperature  of  the  locality, 
its  temperature  range  or  the  difference  between  the  mean  temperatures  of 
its  coldest  and  warmest  months  is  20°  C.  Second,  that  its  annual  curve  of 
temperature  change  is  of  the  usual  type  for  cold  regions.  Third,  that  the 
rate  of  precipitation  is  uniform  throughout  the  year.  The  line  C  D  E  is 
the  curve  of  snow  accumulation.     For  all  temperatures  below  —10°  its 

MON  I 19 


— AO  —to  O  +IO' 

Fig.  35. — Fir.st  Diagram  of  Glaciation  Theory. 


Hori- 


zontal distances  repl'esent  Mean  Annual  Tenii)erature 
in  Centigrade  deffi-ee.s.  Tlie  ordinate^  oi  C  D  E  are 
rates  of  Snowfall  (leas  evaporation).  Tbo  ordinates  of 
A  B  are  rates  of  Melting. 


290  LAKE  BONNEVILLE. 

ordinates  .ire  proportioned  to  the  corresponding  saturation  tensions.  For 
each  point  between  — IC  and  +10'^,  the  ordinate  represents  the  product 
of  the  corresponding  saturation  tension  ])y  tlie  k^ngth  of  winter,  expressed 
as  a  fraction  of  the  year.  The  hue  A  B  is  the  curve  of  mehing.  Each  of 
its  ordinates  represents,  for  the  corresponding  mean  annual  temperature,  the 
product  of  the  lengtli  of  sunruner  into  the  mean  temperature  of  summer. 
To  the  left  of  A  it  coincides  with  the  axis  A  X.  Each  of  these  curves  rep- 
resents a  system  of  ratios,  and  the  unit  in  each  system  is  arbitrarily  assumed. 
Any  other  assiimption  of  relative  magnitude  might  have  been  made  ^^•ith 
equal  propriety,  but  such  assumption  would  not  affect  the  essential  charac- 
ters of  the  curves. 

Since  each  ordinate  of  the  curve  C  D  E  represents  a  rate  of  snow 
accumulation,  as  affected  by  precipitation  and  evaporation,  wliile  each 
ordinate  of  the  curve  A  B  represents  a  rate  of  melting,  the  diti'erential 
ordinate  included  between  corresponding  points  of  the  two  curves  (to  the 
left  of  their  intersection)  represents  that  portion  of  the  winter's  snow  which 
survives  the  summer's  melting.  It  represents  the  net  accumulation.  Its 
maximum  value  is  at  A,  corresponding  to  the  mean  annual  temperature  of 
— 10°.  With  progressive  fall  of  temperature  it  diminislies,  at  first  rapidly 
and  afterward  slowly.  With  progressive  rise  of  temperature  it  diminishes, 
at  first  slowly  and  afterward  rapidly  to  the  point  of  intersection,  I. 

We  may  now,  before  drawing  final  conclusions,  examine  our  postulates, 
and  inquire  what  errors  they  introduce.  In  addition  to  tliose  stated  above 
there  are  several  implied  postulates  Avhich  are  worth}'  of  consideration. 

First,  it  is  assumed  that  the  annual  temperature  range,  or,  more  pre- 
cisely, the  range  of  the  monthly  means  of  temperature,  is  20°  C.  This  is 
not  far  from  the  average  temperature  range  in  existhig  glacier  regions,  but 
there  are  some  localities  where  the  range  is  somewhat  less,  and  others  where 
it  is  much  greater.  The  assumption  of  a  different  range  would  produce  in 
the  diagram  a  pair  of  curves  diftering  in  proportions  but  identical  in  type. 

Secondly,  it  is  ])Ostulated  that  a  clinnge  in  the  general  tenq)erature  is 
not  accompanied  by  a  change  in  tlic  local  annual  temperature  range,  or,  in 
other  words,  that  the  temperature  i-ange  is  constant,  'i'he  2«'ecise  nature  of 
errors  introduced  by  this  postulate  is  not  easily  seen,  but  considerations 


EXAMINATION  OF  POSTULATES.  291 

analogous  to  those  to  which  attention  was  called  in  discussing'  the  variations 
of  wind  velocity  suggest  that  a  rise  in  general  temperature  would  produce 
a  slight  expansion  of  local  temperature  range.  The  corresponding  corrective 
modification  of  the  curves  would  fall  entirely  to  the  right  of  the  ordinate 
A  D,  and  would  be  unimportant. 

Thirdly,  it  is  postulated  that  the  local  annual  curve  of  temperature  is 
of  the  type  usually  observed  in  cold  regions.  If  observation  afforded  us 
information  in  regard  to  the  temperature  cycles  of  n('\('  districts,  their  type 
would  be  the  one  to  employ  in  the  construction  of  our  curves;  but  there  is 
no  reason  to  believe  that  the  error  incurred  by  our  ignorance  of  this  point 
is  considerable. 

Fourthly,  it  is  j)ostulated  that  the  curve  derived  from  the  monthly  means 
fully  represents  the  temperature  oscillations  of  the  year.  This  is  manifestly 
untrue,  for  not  only  is  there  a  diurnal  oscillation,  often  comparable  in  range 
to  the  annual,  but  there  are  also  non-periodic  oscillations  of  considerable 
magnitude.  It  is  a  matter  of  ordinary  experience  that  a  melting  of  snow 
often  takes  place  during  the  warm  jiortion  of  a  day  whose  mean  tempera- 
ture is  below  the  freezing  point,  and  that  precipitation  sometimes  takes  the 
fonn  of  snow  during  the  cold  part  of  a  day  whose  mean  temperature  is  above 
the  freezing  point;  and  that  snows  may  fall  in  tlie  midst  of  summer  and 
thaws  occur  in  the  midst  of  winter.  Thus  the  actual  temperature  range  in 
any  individual  year  is  greater  than  the  range  obtained  by  the  method  of 
monthly  means.  It  is  impossible  to  make  satisfactory  allowance  for  this  in 
the  construction  of  f)ur  cur^'es,  for  the  reason  that  the  importance  of  the 
diurnal  and  non-})eriodic  oscillations  varies  greatly  with  latitude  and  with 
distance  from  the  ocean.  The  curves  as  drawn  represent  sufficiently  well 
the  relations  of  snow  accumulation  and  melting  at  maritime  stations,  but 
not  at  interior  stations.  The  general  nature  of  the  modifications  necessary 
to  adapt  them  to  interior  stations  is  easily  indicated.  With  the  mean  annual 
temperature  at  0°  C,  the  ratios  of  precipitation  and  melting  are  tmaffected 
by  the  neglected  oscillations.  With  the  mean  annual  temperature  at  or 
near  —  10°,  the  ratio  of  precipitation  is  diminished  and  that  of  melting 
increased.  With  the  mean  annual  temperature  at  +  10°,  the  ratio  of  pre- 
cipitation is  increased  and  that  of  melting  diminished.     The  application  of 


292  LA.KE  BONXEVILLE, 

these  corrections  to  the  diaf^'ram  would  lower  the  curve  C  D  E  in  the  im- 
mediate vicinity  of  D,  smoothing-  out  the  angle  at  that  point,  would  leave  it 
unchanged  where  it  intersects  the  ordinate  of  0°,  and  would  carry  the  point 
E  farther  to  the  right.  It  would  raise  the  curve  A  B  at  A,  and  lower  it  at 
B,  leaving  the  central  })ortion  unchanged.  The  j)oint  A,  or  the  intersection 
with  the  horizontal  axis,  woidd  be  thrown  to  the  left. 

Fifthly,  in  the  construction  of  the  cm-ves  no  allowance  was  made  for 
evaporation  during  summer.  The  curve  1)  E  includes  onh'  winter  evapora- 
tion, the  curve  A  B  only  summer  melting.  The  rate  of  evaporation  for 
snow  and  ice  has  its  maximum  at  0°,  its  law  changing  at  that  point.  In 
the  general  law  for  aqueous  evaporation,  the  rate  of  evaporation  is  a  func- 
tion of  the  difference  between  the  saturation  tension  corresponding  to  the 
temperature  of  the  evaporated  substance  and  the  actital  vapor  tension  of 
the  evaporating  air.  Since  snow  and  ice  can  not  rise  in  temperature  above 
0'^,  thev  can  only  be  evaporated  when  the  aqueous  tension  of  the  air  in 
contact  with  them  is  less  than  the  saturation  tension  ior  0°.  If  it  rises  above 
that,  moisture  is  deposited  on  the  ice  as  dew,  instead  of  being  abstracted 
from  it.  In  all  but  very  exceptional  cases  the  range  of  summer  tempera- 
tures under  which  nevd  can  evaporate  is  small — from  0°  to  5°  or  6°.  The 
effect  of  the  evaporation  is  to  retard  the  wasting  of  the  ice,  for  the  energy 
consumed  by  it  is  deducted  from  that  available  for  melting,  and  a  unit  of 
solar  heat  can  melt  seven  times  as  nnich  ice  as  it  can  evaporate.^  The  cor- 
rection, if  applied  to  the  curve  of  melting,  would  slightly  increase  its  upward 
concavity. 

Sixthly,  the  winter  evaporation  embodied  with  the  winter  precipitation 
in  the  curve  D  E  is  tacitly  assumed  to  have  a  rate  corresponding  to  the 
mean  annual  teini)erature;  its  rate  is  reallv  less,  being  a  function  of  the 
mean  winter  temperature.  Au  error  is  thus  manifestlv  introduced,  and  this 
error  is  greatest  for  the  amuial  tem})eratures  corresponding  to  short  winters. 
A  corresponding  correction  of  the  diagram  would  raise  the  line  D  E  by 
amounts  increasing  ])rogTessively  from  D  to  E. 

'The  conditioriH  deteriiiinin<;  tlie  evaporation  of  ice  .iiid  the  formation  of  <le\v  on  glaciers  are 
clearly  set  forth  liy  Heim,  who  cites  experinieut.xl  verifications  by  Diifonr  and  Forel.  See  "  Handlimh 
der  Gletscherkiiudi',"  by  Dr.  Albrecht  Heini,  p.  2yS-'241,  and  Bull.  Soc.  vaudoije  deg  sc.  uat.  1871,  pp. 
4  9-410. 


CORRECTIOK  FOR  POSTULATES. 


293 


Seventhly  and  finally,  it  is  postulated  that  the  precipitation  is  uniform 
throughout  the  year.  Perhaps  no  better  postulate  could  he  made  if"  we 
wished  to  express  the  general  fact  for  the  entire  earth  or  for  a  hemisphere; 
l)ut  oxu-  attention  is  really  restricted  to  a  peculiar  class  of  localities,  namely 
those  in  which  the  climatic  conditions  are  somewhat  favorable  to  the  forma- 
tion of  nevds.  It  is  evident  that  the  massing  of  precipitation  in  winter  is 
a  favorable  condition,  and  we  might  with  propriety  assign  to  our  typical 
locality  a  precipitation  curve  including  a  winter  maximum  and  a  sunnner 
minimum.  Such  a  precipitation  curve  would  increase  all  the  ordinates  of 
the  line  D  E  of  the  diagram,  except  those  at  D  and  at  E. 

Of  these  postulates,  only  the  fourth  and  seventh  materially  aflPect  the 
problem  under  consideration.  The  diagram  (Fig.  35)  represents  sufficiently 
well  the  neve  conditions  at  stations  of  maritime  climate  where  the  precipi- 
tation is  equally  distributed  through  the  seasons,  but  it  fails  to  represent 
them  for  stations  of  continental  climate,  and  for  stations  at  wdiich  the  annual 
curve  of  precipitation  has  a  decided  maximum.  It  is  desirable  to  give 
graphic  expression  to  these  classes  of  stations  also,  but  it  is  unnecessary  to 
consider  them  separately,  since  the  modifications  which  they  occasion  affect 
different  portions  of  the  diagram. 
Both  types  are  combined  in  Fig.  36, 
the  computations  for  which  assumed 
a  mean  diurnal  temperature  range  of 
10'^,  and  a  midwinter  precipitation 
twice  as  great  as  that  of  midsummer. 

The  vertical  distances  between 
corresponding  points  of  the  lines  GDI 
and  X  A  I,  as  before  stated,  represent 
annual  additions  to  the  n^ve  at  a 
particular  locality,  each  individual 
vertical  corresponding  to  a  particular  mean  annual  temperature  of  the  place. 
The  position  of  the  maximum  vertical  indicates  the  temperature  at  which 
the  annual  neve  increment  reaches  its  maximum.  The  position  of  the 
intersection  of  tlie  two  lines  indicates  the  limit  to  ndvi  formation,  or  the 
annual  temperature  above  which  niv6  does  not  gather. 


+/0-  '  X 

Fii::.  36.  — Second  Diagram  of  Glaciutiuu  Theory.  Ilori- 
zontul  distaucua  ii'preseut  uiuau  auiiual  tmuperaturo  iu 
Centigrade  dejireea.  The  orilinatea  o{  C  V  E  are  rates  of 
Snowfall  (less  evaporation).  The  oidinatea  of  A  11  are 
rates  of  Melting. 


294  LAKE  BONNEVILLE. 

We  may  repeat,  too,  that  as  the  ordiiiates  of  tlie  two  curves  express 
ratios  only,  the  amplitude  given  to  the  curves  of  the  diagram  is  a  mere 
matter  of  convenience.  Their  relative  amplitude,  on  the  other  hand,  is  a 
matter  of  importance,  to  which  some  attentii)n  nuist  be  given  before  the 
curves  can  be  pro])erly  interpreted.  Assuming  that  the  amplitude,  with 
reference  to  the  axis,  of  the  curve  of  melting,  A  B,  is  fixed,  the  amplitude 
of  the  curve  of  snowfall,  C  D  E,  varies  with  the  precipitation  as  controlled 
by  local  conditions.  For  localities  of  great  precipitation  its  amplitude  is 
great,  and  the  point  of  intersection,  I,  falls  to  the  right  of  its  mean  position. 
For  localities  of  less  precipitation  the  amplitude  is  less,  and  the  point  of 
intersection  falls  farther  to  the  left.  For  localities  whose  precipitation  does 
not  exceed  the  evaporation,  the  amplitude  becomes  negative,  the  curve  falls 
below  the  axis,  and  the  expression  for  the  ndvd  increment  has  no  positive 
value.  Now,  for  the  localities  of  existing  n^vc^s  the  highest  mean  annual 
temperature  is  approximately  0°,  and  it  may  be  assumed  without  material 
error  that  for  the  most  favorable  localities  the  amplitude  of  the  snowfall 
curve  is  such  as  to  bring  its  point  of  intersection  with  the  melting  curve  on 
the  ordinate  corresponding  to  0°.  The  snowfall  curve  of  the  diagram  there- 
fore has  an  amplitude  near  the  maximum,  and  represents  a  locality  of  great 
preci})itation  (as  compared  to  other  localities  at  the  same  temperature)  and 
highly  favorable  to  the  accumulation  of  n^v^. 

In  different  localities  the  highest  annual  temperature  consistent  with 
nt^ve  accumulation  may  be  as  low  as  — 10°  or  as  high  as  0°,  or,  more  accu- 
rately (giving  heed  to  the  first  postulate),  the  range  of  the  limit  is  from  the 
climate  whose  mean  midsummer  temperature  is  0°  to  the  climate  whose 
mean  annual  temperature  is  0°.  Tlie  maximum  neve  increment  in  the  case 
represented  by  the  diagram  is  at  — 9°.  With  the  greatest  admissible  ami)li- 
tude  of  the  snowf^xll  curve  it  Avould  be  at  about  — 8°.  With  a  very  .small 
positive  amplitude  it  would  be  a  few  degrees  below  — 1()°.  It  does  not 
vary  far  in  either  direction  from  — 10°,  or  (admitting  the  tpialitication  of 
the  first  postulate)  frt)m  the  animal  temperature  corresponduig  to  a  mid- 
summer temperature  of  0°. 

For  each  locality  there  is  a  definite  temperature  limit  above  which 
n6v6  can  not  accumulate.     Starting  from  this  limit,  the  maximum  rate  of 


GLACIATION  AND  GENERAL  TEMPERATURE.  295 

nevd  increment  is  reached  by  a  fall  of  temperature  ainounting-  to  something 
less  than  half  the  annual  range  for  the  locality.  With  continued  lowering 
of  temperature,  there  is  progressive  diminution  in  the  amount  of  snow 
annually  added;  but,  within  the  range  of  temperature  the  consideration  of 
which  is  demanded  bv  our  practical  problems,  there  is  no  uidicatidn  (if  an 
inferior  temperature  limit  to  the  accumulation  of  snow. 

In  applying  these  principles  of  ndvd  increment  to  the  correlation  of 
glacier  expansion  with  its  appropriate  temperature  change,  it  is  convenient 
to  consider  two  cases.  First,  let  us  conceive  a  mountain  slope  all  parts  of 
which  have  the  same  type  of  annual  snowfall  curve.  The  actual  snowfall 
at  each  level  depends  upon  the  temperature  corresponding  to  that  altitude. 
A  certain  temperature  marks  the  lower  limit-  of  nijve  increment,  and  there- 
fore the  lower  limit  of  ndvd.  From  this  limit  upward  to  the  summit,  the 
whole  surface  receives  an  annual  increment  of  snow,  which  is  not  dissipated 
in  place  but  is  eventually  converted  into  ice  and  flows  downward  to  be 
melted  below  the  niv6  limit.  The  maximum  increment  to  the  nivi  occurs 
some  thousands  of  feet  above  the  limit — according  to  local  conditions  it  may 
be  1,000  feet  or  10,000  feet.  -  A  volume  of  ice  equivalent  to  the  total  annual 
n^v^  increment  passes  each  year  from  the  n^vt^  zone  to  the  zone  of  melting, 
and  the  distance  to  which  the  ice  advances  is  a  function  likewise  of  the 
annual  supply  aiforded  by  the  ndv^.  Assume,  now,  that  the  general  tem- 
perature rises  and  is  continued  at  a  higher  rate  until  the  forces  once  more 
reach  an  equilibrium.  With  the  rise  of  the  isothermal  planes  the  neve  limit 
rises,  and  likewise  all  elements  of  the  nivii  sheet.  The  zone  of  nevd  accu- 
mulation loses  a  strip  at  its  upper  margin  and  the  total  amount  of  the  ndv^ 
increment  becomes  less.  The  annual  tlow  of  ice  from  the  zone  of  ntv6  to 
the  zone  of  melting  is  correspondingly  less,  and  being  sooner  melted,  it 
maintains  a  narrower  zone  of  melting.  Thus  in  every  way  a  rise  of  tem- 
perature diminishes  the  glaciated  area. 

Consider  now  a  spot  which  by  its  topographic  configuration  is  rendered 
favorable  to  the  accumulation  of  nevd,  although  surrounded  by  a  region 
unfavorable  to  such  accumulation.  Assume  that  the  temperature  is  at  iirst 
high,  and  then  falls  with  secular  slowness.  As  soon  as  it  passes  the  local 
limit,  the  foi-mation  of  n^ve  begins.     With  still  lower  temperatures,  the 


296  LAKE  BONNEVILLE. 

annual  increment  becomes  greater,  up  to  a  certain  maximum,  and  afterward 
becomes  less.  As  soon  as  the  temperature  permits  the  accuirmlation  of 
neve,  motion  ensues,  and  a  stream  of  ice  flows  from  the  locality.  The  .stream 
is  at  first  small,  rapid,  and  short:  rapid,  because  ice  moves  most  freely  wlien 
near  its  melting  ],)oint ;  small,  because  it  is  rapid;  and  .short,  because  little 
descent  is  necessary  to  bring  it  into  the  zone  of  melting.  As  the  tempera- 
ture falls,  the  motion  is  retarded  by  diminishing  plasticity,  and  to  maintain 
the  annual  discharge  a  greater  cross-section  is  necessary.  The  annual  dis- 
charge, being  equal  to  the  annual  ndvd  increment,  is  at  first  inci-eased  and 
afterward  diminished.  Its  increase  conspires  with  the  impairment  of  plas- 
ticity to  enlarge  the  cross-section;  its  final  decrease  at  very  low  tempera- 
tures tends  in  the  opposite  direction,  and  may  ultimately  overpower  the 
effect  of  diminishing  plasticity  and  diminish  the  cross-section ;  but  the  tem- 
pera tiu'e  of  maximum  cross-section  must  lie  far  below  the  temperature  of 
maximum  ndve  increment.  Within  the  limits  of  our  practical  problem,  the 
depth  and  breadth  of  the  glacier  increase  with  fall  of  temperature;'  and  its 
length  increases  at  the  same  time,  because  the  conditions  of  melting  are  less 
and  less  favorable  the  lower  the  temperature.  Conversely,  a  rise  of  tem- 
perature diminishes  at  once  the  glaciated  area  and  the  depth  of  the  ice. 

A  moment's  reflection  will  show  that  into  these  two  cases  all  actual 
cases  are  resolvable;  and  as  their  indication  is  identical,  we  conclude  in 
general  that  a  universal  rise  of  terrestrial  temperature,  such  as  would  be 
produced  by  an  increased  supply  of  solar  heat,  would  everywhere  diminish 
the  magnitvide  of  neves  and  glaciers. 

It  has  been  previously  pointed  out  that  an  increase  of  glaciation  in  the 
Sierra  and  the  Wasatch  by  means  of  a  general  elevation  of  the  district 

'Snow  is  ordinarily  welded  into  ice  by  the  freezing  of  interstitial  water;  bntatlow  tenipeiatunH 
there  is  no  interstitial  water,  and  the  welding  can  be  accomplished  only  by  great  prcssnre.  In  regions 
where  the  temperature  never  rises  to  0\  a  great  depth  of  snow  is  necessary  to  the  con.solidation  of  iho 
lower  Layers.  From  the  nature  of  the  case,  this  dry  welding  can  not  be  observed  in  natnre,  but  its 
actuality  has  been  demoustnated  in  the  laboratory  by  the  expcrirntnts  of  Mr.  E.  Ilnngerford  (Amer. 
Jour.  Science,  vol.  23,  18H2,  p.  434).  If  our  existing  glaciers  include  any  which  arise  in  this  way, 
tho.se  of  the  Antarctic  regions  are  probably  of  this  class.  In  small  di.stiicts  of  great  cold,  such  as  the 
tops  of  high  mountains,  the  dry  snow  is  drifted  freely  by  the  wind  and  finds  its  nay  to  lower  levels 
instead  of  accumulating  in  great  mass  whore  it  falls. 

It  is  conceivable  that  an  extremly  cold  climate  would  demand  for  the  consolidation  of  its  snow 
a  greater  pressure  than  would  ever  be  realized  by  its  accumulation,  but  such  a  hypothetical  case  is 
beyond  the  limits  of  the  Pleistocene  problem. 


FRESn-WATER  SHELLS.  297 

would  be  accompanied  by  a  lowering  of  the  temperature  of  the  district; 
and  that  a  similar  lowering  of  the  temperature  would  accompany  an  in- 
crease of  glaciation  by  the  encroachment  of  the  Pacific  on  the  California 
coast,  by  the  lowering  of  the  temperature  of  the  Pacific,  or  by  a  small 
change  in  the  direction  of  the  great  air  current.  Adding  now  that  a  lower- 
ing of  temperature  through  the  lessening  of  solar  heat  would  increase  the 
glaciation,  we  may  continue  the  discussion  of  the  Pleistocene  lakes  with  the 
assurance  that  if  they  were  contemporaneous  with  the  ancient  glaciers  of 
the  Sierra  Nevada,  they  occurred  during  epochs  of  relative  cold. 

THE  EVIDENCE  FROM  MOLLUSCAN   LIFE. 

The  hydrographic  basins  of  Lake  Bonneville  and  Lake  Lahontan  have 
the  same  latitude,  lie  at  sensibly  the  same  altitude,  and  are  in  general 
characterized  by  identical  physical  conditions.  They  are  moreover  con- 
tiguous, and  separated  by  no  barrier.  There  is  thus  every  reason  to  group 
them  together  as  a  single  homogeneous  fauna!  district,  and  it  will  be  advan- 
tageous so  to  regard  them  in  discussing  the  climatic  interpretation  of  the 
vestiges  they  contain  of  Pleistocene  life.  The  Bonneville  fauna  has  been 
enumerated  in  an  earlier  chapter.  The  Lahontan  ftxuna  is  described  by 
Russell  in  his  monograph.^  Each  is  meager,  but  taken  together  they  afford 
bases  for  climatic  inference  in  two  biologic  divisions,  the  division  of  fresh- 
water mollusks  and  the  division  of  vertebrates. 

The  fresh-water  mollusks  were  collected  as  opportunity  offered  by 
Russell's  parties  and  my  own,  and  specimens  were  sent  to  Call  for  examina- 
tion. His  preliminary  results  were  of  such  interest  that  it  was  determined 
to  afford  him  an  opportunity  to  study  the  fossils  in  the  field  and  to  collect 
their  living  representatives  in  the  same  district.  He  accordingly  visited 
Utah  and  Nevada  in  the  summer  of  1883  and  spent  two  months  in  gather- 
ing the  recent  and  Pleistocene  shells.  The  combined  collections  were  after- 
ward studied  by  him  and  became  the  subject  of  an  essay  on  the  Pleistocene 
and  recent  mollusca  of  the  Great  Basin,  which  was  published  as  a  Bulletin 
of  the  Survey.^  The  statements  ^\hich  follow  are  partly  based  on  this 
publication. 

'  Geological  History  of  Lake  Lahontan,  pp.  23S-249. 

^On  the  Quaternary  and  Recent  mollusca  of  the  Great  Basin.  By  R.  Ellsworth  Call.  Bull. 
U.  S.  Geol.  Survey  No.  11,  1884,  pp.  13-07. 


298 


LAKE  BONNEVILLE, 


As  appears  from  the  following  table,  18  species  have  been  obtained 
from  the  Bonneville  strata  and  23  from  the  Lahontan.  Eight  of  these  are 
identical,  making  the  whole  number  of  species  from  the  entire  district  33. 
The  number  of  recent  species  known  in  the  same  district  is  36,  and  2G  of 
these  are  specifically  identical  with  the  Pleistocene  forms.  The  entire 
known  fauna  of  the  district,  recent  and  Pleistocene,  comprises  43  species. 


Table  XI. — Fresh-water  Shells  in  the  BonnevilU-Lahontan  Area. 
R  =  Recent.    B  =  Bonneville.    L  =  Lahontan. 


Unionklai. .. 
CorbiculidsB 

Limnseida)  . 


Margaritana  niargaritil'era,  Liiiii. 

Aiiodonta  mittalliana,  Lea 

Sphuirium  dentatuni,  Hald 

striatinum,  Lam 

Pisidiuiii  coiiipressum,  Prime  

abditiim,  Hald 

ultramontauuin,  Prime  . 

Helisoma  corpulentiis,  Say 

ammon,  Gould 

trivolvis,  Say 

suborenatus,  Carp 

Gyraulus  parvus,  Say 

vermicularis,  Gould 

Menotiis  opercularis,  Gould 

Limnophysa  palustris,  Miill 

sumassi,  Baird 

liumilis,  Say 

bulimoides,  Lea 

bounevillensis,  Call 

desid  iosa,  Say 

caperata,  Say 

Limniea  stagnalis,  Linn 

Radix  aiiipla,  Migli .. 

Pbysa  gyrina,  Say 

bumerosa,  Gould 

ampullacea,  Gould 

beterostropba;  Say 

elliptica,  Lea 

lordi,  Baird 

Pompliolyx  effusa,  Lea 

Carinifex  uowberryi,  Lea 

Aucylus  newberryi,  Lea 

sp.  iudet 


R 


L 
L 
L 
L 
L 

L 
L 
L 
L 

L 
L 
L 
L 
L 
L 
L 


L 
L 
L 


SHELLS  OF  BONNEVILLE  AND  LAHONTAN. 


299 


Tablk  XI. — Fresh-waler  Shells  in  ike  Bonneville- Lahontan  zlrea— Continued. 
R  =  Recunt.    B  =  Bonneville.    L  =  Lahontan. 


R 
R 

15 
B 
B 

B 
B 
B 

L 
L 
L 

ValvatidiP 

Pomatiopsidie 

Fluminicola  fusca,  HaUl 

Pyrgula  nevadensis,  Steams 

R 
R 
R 
R 
R 

Bythiuella  biuneyi,  Tryoii 

Valvatai  virens,  Tryon  ..   .... . . 

sinccra.  Sav        ... ..-.- 

Poniatiopsis  1  ustrica,  Sav        ... ...... 

Considering  that  the  search  which  has  brought  to  light  these  43  species 
has  been  far  from  exhaustive,  alike  in  the  existing  waters  and  in  the  Pleis- 
tocene strata,  it  is  somewhat  remarkable  that  five-sixths  of  the  fossil  fonns 
are  known  also  in  the  recent  waters  of  the  district;  and  we  are  permitted, 
if  indeed  we  are  not-  compelled,  to  regard  the  Pleistocene  and  recent  faunas 
as  actually  identical.^  The  differences  between  the  known  faunas  are  there- 
fore referable  to  accidents  of  discovery,  and  can  not  be  given  a  climatic 
interpretation.  If  however  we  restrict  attention  to  the  26  identical  species 
and  compare  the  fossil  with  the  living  representatives,  we  find  a  varietal 
difference  of  very  striking  character.  The  fossil  shells  are  smaller  than 
the  li\-ing  shells  of  the  same  species.  This  fact  was  discovered  by  Mr.  Call 
during  his  preliminary  examination  of  the  fossils  and  Avas  afterward  verified 
by  an  elaborate  series  of  measurements.  Not  all  of  the  26  species  were 
collected  in  sufficient  numbers  to  afford  a  good  determination  of  the  average 
size,  but  enough  of  them  were  well  represented  to  give  assurance  of  the 
generality  of  the  law  of  difterence. 

'This  inference  .-uliiiits  of  a  niatliem.atical  expression.  \i  the  streams  and  the  .strata  contain  not 
only  the  same  nnmber  of  8i)ecii'.s  bnt  the  same  species,  and  if  eacli  of  these  is  equally  discoverable,  then 
the  most  probable  nnmber  of  identities  or  coincidences  between  the  known  living  species  and  the 
known  fossils  is  expre.ssed  by  the  product  of  the  number  of  living  species  known  into  the  number  of 
fossil  species  known,  divided  by  the  total  number  of  species  in  the  entire  fauna.  We  do  not  know  this 
total,  but  it  surely  exceeds  4;i;  considering  how  very  small  a  portion  of  the  entire  field  has  been 
searched,  there  can  bo  no  exaggeration  in  estimating  it  at  GO.     The  mathematical  formula  then  gives 

— — —  =  20  as  the  most  probable  number  of  identical  forms  in  the  fossil  and  recent  collections.     In 

bu 
point  of  fact,  not  all  species  are  equally  discoverable.     Some  are  relatively  conspicuous  and  others 
relatively  ubiquitous,  and  these  would  be  more  likely  to  occur  in  both  collections  aud  thus  increase 
the  number  of  identical  forms.     The  number  of  coincidences  actually  observed,  20,  is  therefore  in 
apparent  harmony  with  the  number  theoretically  deduced. 


300  LAKE  BONNEVILLE. 

Depauperation  and  coid.-To  accouiit  for  tliis  difFereiicG  ill  size,  several  hypoth- 
eses were  suggested,  but  only  two  appeared  worthy  of  discussion,  ;ind  to 
these  Mr.  Call  directed  his  attention.  Tlie  first  hypothesis  is  tliat  oi  cold, 
the  second  that  of  salinity.  It  was  already  known  that  the  life  of  each 
molluscan  species  is  conditioned  by  a  certain  range  of  temperature  and 
by  a  certain  range  of  salinity,  and  it  was  naturally  inferred  that  a  lowering 
of  temperature  insufficient  to  cause  extinction  iniglit  induce  depauperation, 
and  that  a  similar  effect  might  be  produced  l)v  the  presence  in  the  ancient 
lake  waters  of  a  small  percentage  of  saline  matter.  For  the  pur})ose  of 
testing  these  inferences,  comparative  measurements  were  made  of  shells  now 
living  in  waters  of  various  temperatures,  and  also  of  shells  now  living  in 
waters  differing  in  salinity — all  specimens  being  obtained  from  the  Bonne- 
ville-Lahontan  district. 

Church  Lake,  near  Salt  Lake  City,  Utah,  has  an  altitude  of  about  4,300 
feet;  Little  Gull  Lake,  in  the  Mono  Basin,  at  the  eastern  l)ase  of  the  SieiTa 
Nevada,  lies  three  degrees  farther  south,  and  has  an  altitude  of  about  7,700 
feet.  The  temperature  of  the  second  locality  is  not  known  as  a  matter  of 
observation,  but  a  comparison  of  topogTa])hic  relations,  and  especially  of 
the  terrestrial  floras,  leads  to  the  belief  that  there  is  about  as  much  differ- 
ence as  that  indicated  by  the  altitudes,  the  climate  at  Little  Gull  Lake 
being  8  or  10  degrees  (F.)  colder.  From  these  two  lakes  the  same  species, 
Pluisa  ampullacea,  was  obtained  in  the  same  month,  and  comparative  meas- 
urements were  afterward  made  of  series  of  adult  shells.  The  ratio  of  size 
(linear)  was  found  to  be  100  (Church  Lake)  :  86  (Little  Gull  Lake). 

Honey  Lake,  California,  and  Warm  Spring  Lake,  Utah,  lie  at  nearly 
the  same  altitude  and  latitude.  Their  temperatures  are  not  known  l)y 
observation,  but  as  Warm  Spring  Lake,  being  of  small  area,  lias  for  its 
principal  tributary  a  large  spring  of  water  at  128°  F,  it  is  higldy  prol)al)le 
that  its  molluscan  life  is  conditioned  by  the  higher  temperature.  Specimens 
of  Limuoplujsa  italiistris  were  collected  from  both  lakes  and  afterward  meas- 
ured, the  averages  showing  a  ratio  of  100:88  iu  favor  of  tlie  specimens 
from  the  Avarm  lake. 

These  two  illustrations  support  tlie  hypothesis  that  within  the  climatic 
range  of  the  Great  Basin  a  low  tt'inperature  of  lake  water  is  less  favorable 
to  the  growth  of  gasteropods  than  a  high  tem2)erature. 


CLIMATIC  TESTIMONY  OF  FOSSIL  SHELLS.  301 

Depauperation  and  Saiinity.-In  Seeking  fov  natui'al  examplos  illustrating  the 
effect  of  salinity,  there  was  not  the  same  success  in  the  elimination  of  coin- 
cident differences  of  station.  Some  of  tlie  brackish  lakes  of  the  Lahontan 
district  contain  living  shells,  liut  these  are  not  aA'ailable  for  comparison, 
because  the  same  species  have  not  also  been  discovered  in  the  fresh  waters 
of  the  district.  Recourse  was  therefore  had  to  brackish  si)rings,  and  the 
shells  inhabiting  these  were  compared,  one  species  with  the  denizens  of  a 
fresh-water  lake  and  another  with  the  denizens  of  fresh-water  ponds.  The 
brackish  springs  affording  the  shells  rise  from  the  Bonneville  marls  at  the 
eastern  base  of  the  Promontory  range  in  Utah,  and  are  not  thermal.  Their 
waters  were  not  analyzed,  and  their  salinity  was  tested  only  by  taste.  It 
was  estimated  to  be  less  than  0.5  j^er  cent.  Specimens  of  Limuophijsa 
palustris  from  these  spring's  were  compared  with  other  specimens  from 
Honey  Lake,  and  found  to  be  only  seven-eighths  as  large,  the  precise  ratio 
being  87  :  100.  Specimens  of  Ph//sn  gi/rina  were  compared  with  other  speci- 
mens from  fresh  ponds  near  Salt  Lake  City,  and  found  to  have  a  linear  ratio 
of  82  :  100.  It  appears,  then,  that  salinity  is  quite  as  competent  as  cold  to 
determine  the  depauperation  of  fresh-water  gasteropods. 

We  are  thus  led  to  inquii'e  whether  there  is  any  independent  evidence 
in  regard  to  the  freshness  or  salinity  of  the  waters  of  the  Pleistocene  lakes. 
In  the  case  of  Lake  Lahontan  the  presumption  is  strongly  in  favor  of 
salinity,  for  the  lake  has  no  outlet,  and  though  it  may  jiossibl}'  on  more 
than  one  occasion  have  buried  its  saline  matter  under  playa  deposits  and 
thus  freshened  its  water,  we  cannot  say,  with  reference  to  any  of  the  col- 
lected shells,  that  they  belong  to  any  such  fresh-water  epoch.  The  testi- 
mony afforded  Ijy  the  depauperation  of  the  Lahontan  shells  is  therefore  not 
available  in  the  climatic  problem.  The  case  of  Lake  Bonneville  is  different, 
for  during  its  second  expansion  it  freshened  its  water  by  (tverflow,  and  the 
sediment  deposited  durhig  the  second  rise  is  clearly  differentiated.  We 
cannot  indeed  demarcate  the  })ortions  of  this  bed  which  Ijelong  respectively 
to  the  epoch  of  rising  water,  to  the  epoch  of  outflow,  and  to  the  epoch  of 
desiccation;  but  we  know  from  the  phenomena  of  the  shore-lines  that  the 
rise  of  the  water  was  slow,  that  the  discharge  was  long  sustained,  and  that 
the  final  subsidence  was  rapid  down  to  the  level  of  the  Stansbury  shore- 


302 


LAKE  BONNEVILLE. 


line.  We  are  thus  enalilcd  to  assert  with  much  confidence  that  the  upper 
layers  of  the  White  Marl  between  the  levels  of  the  Provo  and  Stansl)ury 
shore-lines  were  deposited  while  the  lake  was  freshened  by  outflow.  And 
finding-  that  shells  gathered  from  those  layers  are  small  in  size,  we  accept 
their  depauperation  as  evidence  of  a  colder  climate.  The  sulijoiued  table 
shows  measurements  of  25  adult  shells  collected  from  these  layers  near  the 
town  of  Kelton,  and  gives  comparative  measurements  of  IS  individuals 
found  living  in  Utah  Lake,  the  largest  body  of  fresh  water  within  the 
Bonneville  area.  The  ratio  of  linear  dimensions  is  approximately  3  :  4,  the 
recent  shells  being  the  larger.  It  is  noteworthy  that  while  each  series 
exhibits  considerable  range  in  size,  only  two  or  three  of  the  living  shells 
are  as  small  as  the  largest  of  the  fossils. 

Table  XII.  Meaauremcnts  of  Fluininicola  fusea. 


Living  in  Utah  Lake. 

Fossil  in  Upper 
Bonneville. 

Length. 

Breadth. 

Length. 

Breadth. 

mm. 

mm. 

mm. 

mm. 

12.50 

8.10 

9.94 

6.62 

12.00 

7.80 

9.50 

6.40 

11.90 

8.20 

9.10 

5.50 

11.72 

7.14 

9.00 

5.56 

11.50 

8.00 

8.50 

5.56 

11.30 

7.64 

H.44 

5.60 

11.00 

7.70 

8.36 

5.70 

10.80 

8.00 

8.34 

5.22 

10.50 

0.70 

8.30 

0.10 

10.50 

6.52 

8.30 

5.54 

10.50 

6.40 

H.20 

5.32 

10.24 

fi.  .'•.0 

8.  10 

5.08 

10.  22 

0.90 

8.10 

5.50 

10.10 

7.00 

8.08 

5.28 

10.00 

7.24 

8.06 

5.56 

9.70 

6.72 

8.00 

5.34 

9.70 

6.52 

7.96 

6.50 

9.52 

7.00 

7.94 

5.50 

10.76 

7. 2;? 

7.82 
7.80 

5.40 
6.20 

7.72 

5.38 

7.60 

5.00 

7.58 

5.40 

7.46 

5.  32 

7.24 

4.98 

8.22 

5.50 

CLIMATIC  TESTIMONY  OF  FOSSIL  BONES.  303 

THE  EVIDENCE  FROM  VERTEBRATE  LIFE. 

The  Pleistocene  luaiuiiiiils  tliiis  tar  discovered  in  the  Bonneville  and 
Lahontan  Basins  are  few  in  number.  Proboscidean  bones  {Elephas  or 
Mastodon^  were  found  in  the  "Intermediate  Gravels"  of  the  Lahontan  Basin 
(equivalent  to  gravels  of  the  Inter-Bonneville  epoch),  in  the  Upper  Lahon- 
tan beds  (equivalent  to  the  White  Marl),  and  in  a  bog  resting  on  the  White 
Marl.  Bones  of  a  horse  (Equus),  of  an  ox,  and  of  a  llama,  and  an  obsidian 
arrow  head,  were  found  in  the  Upper  Lahontan.^  Bones  of  musk-ox  dis- 
covered near  Salt  Lake  City,  though  of  doubtful  age,  are  presumptively 
Pleistocene. 

The  list  is  greatly  extended  by  including  the  fauna  discovered  by  Mr. 
C.  H.  Sternberg  near  Christmas  Lake,  Oregon.  The  locality  was  afterward 
visited  by  Mr.  Russell,  who  found  the  containing  formation  to  be  a  lacus- 
trine deposit  surrounded  by  a  shore-line,  and  otherwise  agreeing  in  its  phys- 
ical relations  with  the  Bonne^^lle  and  Lahontan  and  other  Pleistocene  beds 
of  the  Great  Basin.  The  horizon  of  the  vertebrate  remains  is  close  to  the 
top  of  the  formation,  indicating  approximately  the  same  date  as  that  of  the 
White  Marl.  Cope  has  studied  the  bones  biologically,  and  from  him  we 
learn  that  the  fauna  includes  the  coyote,  a  beaver,  and  two  species  of  gopher; 
and  of  extinct  mammals,  the  mammoth,  an  otter,  a  giant  sloth,  two  species 
of  horse,  three  of  llama,  and  a  deer.  It  includes  also  the  copt,  three  living 
grebes,  three  living  geese  and  one  extinct  species,  an  extinct  cormorant, 
and  an  extinct  swan.^ 

In  order  to  ascertain  the  bearing  of  these  vestiges  on  the  question  of 
the  contemporaneous  climate,  attention  Avill  be  given  to  the  present  climatic 
and  geographic  range  of  such  of  the  species  as  yet  survive,  and  also  to  the 
present  range  of  the  genera  to  which  extinct  species  belong. 

Man  is  now  cosmopolitan.  It  is  known  that  in  Pleistocene  time  he 
lived  near  the  margins  of  P]uropean  and  Ameiican  ice  sheets,  but  his  con- 
temporaneous equatorial  raiige  is  not  ascertained.  The  coyote,  Canis  la- 
trans,  ranges  southward  to  the  plateau  of  Mexico  and  northward  to  the  Sas- 
katchewan Plains.     Near  its  northern  limit  the  local  annual  temperature  is 

'  Russell.     Geological  History  of  Lake  Lahoutau,  pp.  238-9,  246-9. 
'Bull.  U.  S.  Survey  Terrs.,  vol.  4,  1878,  p.  389. 


804  LAKE  BONNEVILLE. 

about  tweuty  degrees  lower  than  at  Christmas  Lake;  near  its  southern  limit, 
more  than  twenty  degrees  liigher. 

Tlioniomys  talpoidcs,  a  pocket  g02)her,  ranges  from  Kansas  to  tli(;  Assini- 
boin  River,  its  range  including  climates  slightly  warmer  and  also  from  ten 
to  fifteen  degrees  cooler  than  that  of  Christmas  Lake.  ThoiiioDujs  rlusius, 
being  known  only  in  its  type  specimen,  has  no  range.  The  climate  of  its 
sole  known  locality,  Bridger's  Pass,  Wyo.,  is  five  or  ten  degrees  cooler  than 
that  of  Clu-istmas  Lake. 

The  beaver  reported  is  Castor  fher,  the  European  species;  but  as  the 
distinctness  of  the  American  form  has  been  denied,  it  is  possible  that  no 
discrimination  is  here  intended.  The  European  beaver  lives  in  northern 
and  central  Europe;  the  American  ranges  from  Arizona  to  the  Arctic  Circle. 

Tlie  musk-ox  is  now  restricted  to  that  part  of  North  America  lying 
north  t)f  the  sixtieth  parallel.  The  most  genial  climate  of  its  range  is  far 
more  severe  than  that  of  the  Salt  Lake  Valley,  but  ma}'  perhaps  be  com- 
pared witli  tliat  of  the  recesses  of  the  Wasatch  and  Uinta  mountains.  Dur- 
ing the  Pleistocene  it  abounded  on  the  plains  of  Siberia  as  Avell  as  in  Ger- 
many, France  and  England. 

The  other  mammalian  species  are  all  extinct,  and  one  only  is  known 
to  have  climatic  significance.  The  mammoth  was  characteristic  of  the 
European  Pleistocene,  and  was  distinguished  from  living  elephants  by  its 
hairy  coat. 

The  modern  otters  belong  to  temperate  and  sub-arctic  faunas,  and  so 
do  deer  of  the  genus  Cerviis.  The  llamas  are  at  home  in  the  mountains  of 
South  America,  and  range  southward  to  Terra  del  Fuego. 

Modern  representatives  of  the  horse  genus  live  in  tropical  and  tem})er- 
ate  climates,  l)iit  in  Plei.stocene  times  they  shared  with  otters  iuid  ilccrs  thr 
boreal  climate  of  England. 

Of  the  climate  suited  to  the  fossil  sloth,  Mijlodoit  sodaVis,  we  have  no 
better  evidence  than  is  afforded  by  his  association  with  this  fauna. 

The  coot,  the  grebes,  and  the  geese  all  range  far  to  the  north  and  to 
the  south  of  the  Christmas  Lake  localitv.  The  coot  ranges  from  Alaska  to 
Central  America.  Podiceps  occldentalis  is  knmvn  to  i-auge  from  Slexico  to 
northern  Manitoba,  P.  californicus  from  Guatemala  to  Great  Slave  Lake, 


CLIMATIC  TESTIMONY  OF  FOSSIL  BONES.  305 

PodUymhus  podiceps  from  South  America  to  British  Possessions.  Anser 
canadensis  extends  from  the  Arctic  Circle  to  Mexico,  A.  albifnms  yamhdi 
from  Aliiskii  to  Texas,  A.  nigricans  from  the  Arctic  Circle  to  the  peniiisvila 
of  California. 

The  extinct  swan  and  cormorant  likewise  belono;  to  genera  of  consid- 
erable  range.  Though  Cyynus  and  (Jraculus  occur  chiefly  in  the  temperate 
zone,  they  overpass  both  the  tropic  and  the  polar  circle. 

The  avian  life  manifestly  throws  no  light  on  the  question  of  climate, 
and  the  same  may  be  said  of  man,  the  coyote,  the  beavei',  the  otter,  the 
deer,  the  horses,  the  llamas,  and  the  sloth.  The  presence  of  the  gopher 
comports  with  the  idea  that  the  climate  of  the  lacustrine  epoch  did  not  differ 
widely  from  the  present  climate.  Tlie  mammoth  favors  the  view  that  the 
climate  was  cooler.  The  musk-ox  speaks  more  decidedly  of  cold,  but  his 
evidence  is  doubly  indefinite;  first,  because  he  may  have  lived  on  the  adja- 
cent high  mountains  instead  of  in  the  Salt  Lake  Valley;  second,  because 
we  do  not  know  whether  he  lived  during  a  lacustrine  or  during  an  inter- 
lacustrine  e))och. 

All  told,  the  evidence  from  vertebrate  life  appears  to  me  not  merely 
inconclusive  but  valueless.  Temperature  is  one  of  a  complex  of  factors 
constituting  climate.  Climate  is  one  of  a  complex  of  conditions  limiting 
the  distribution  of  vertebrate  species.  It  is  not  safe  to  assume  in  the  case 
of  an  individual  species  that  temperature  is  tlm  important  or  controlling- 
factor  and  then  draw  inferences  in  regard  to  temperature;  only  the  cumu- 
lative testimony-  of  a  ftiuna  can  yield  ti-ustworthy  conclusions. 

The  availaljle  biotic  evidence  is  therefore  restricted  to  the  testimony 
of  the  fresh-water  mollusks,  and  this,  if  I  understand  it  aright,  ])oints  to 
the  conclusion  that  the  lake  epochs  were  epochs  of  relative  cold.  So  fur  as 
it  goes,  it  favors  the  correlation  of  ice  maxima,  witli  water  maxima. 

THE  EVIDENCE   FROM   ENCROACHING  MORAINES. 

As  first  announced  by  Emmons,  the  glacier  that  formerly  descended 
Little  Cottonwood  Canyon  from  the  Wasatch  summits  left  its  moraines 
within  the  area  of  Lake   Bonneville.^     A  little  farther  south,  two   other 

'  S.  F.  Emmous.     Geol.  Explor.  of  the  40tli  Parallel,  vol.  2,  ji.  354. 
MON  I 20 


306  LAKE  BONNEVILLE. 

moraines,  Ix'loiiging  to  the  same  group  of  glaciers,  lie  at  about  the  same 
level;  but  with  these  exceptions  all  vestiges  of  the  Pleistocene  glaciers  of 
the  basin  lie  above  the  Bonneville  shore-line. 

In  the  Lahontan  Basin  there  are  no  similar  instances  of  conriguity, 
but  sevci-al  occur  in  the  Mono  Basin,  and  their  ])henomena  are  l^elieved  to 
be  germane  to  the  ])resent  discussion.  The  Pleistocene  histor\'  of  Mono 
Lake  is  recorded,  like  that  of  Great  Salt  Lake,  in  a  sheet  of  sediments  rising 
from  tlie  water's  edge  to  a.  system  of  encircling  shoi-e  traces.  As  deter- 
mined l)y  Russell,  the  expanded  lake  had  no  outlet,"  so  tliat  its  oscillations 
nuist  have  been  determined  purely  by  climate.  The  Mono  drainage  Ijasiu 
is  one  of  the  many  components  of  the  Great  Basin,  and  is  contiguous  to  the 
hydrographic  basin  of  Lake  Lahontan.  Like  Lahontan,  its  water  supply 
is  derived  mainly  from  the  Sierra  Nevada,  which  overhangs  it  on  the  west- 
Analogy  suggests  that  its  lake  surface  rose  and  fell  in  response  to  the  same 
climatic  changes  that  created  and  abated  Lake  Lahontan  and  Lake  Bonne- 
ville, and  this  view  is  sustained  by  the  evident  freshness  of  its  fossil  shore- 
lines. Li  one  respect,  however,  the  correlation  is  incomplete.  The  Bonne- 
ville sediments  and  the  Lahontan  are  each  clearly  divisible  into  two  series, 
separated  by  a  horizon  of  unconformity  by  erosion;  but  in  the  Mono  Basin 
no  satisfactory  division  has  been  made  out.  To  my  mind,  this  negative 
evidence,  which  may  fairly  be  referred  to  imperfection  of  exposure,  has  less 
weight  than  the  climatic  analogy,  and  I  am  decidedly  inclined  to  regard 
the  maxinnim  flood  of  the  Mono  Basin  as  the  ec{uivalent  and  contemporary 
of  the  maximum  ilood  in  each  of  the  larger  basins.  I  shall  therefore  dis- 
cuss tlie  relation  of  the  ancient  sliore-lines  and  sediments  to  the  moraines 
at  the  mouths  of  tlie  Siei'iM  canyons  as  a  part  of  the  evidence  in  regard  to 
th(^  IJonneville  climate.  First  in  onh-r,  however,  are  the  phenomena  of 
till!  B<iune\ill(!  I^asin. 

Wasatch-Bonneville  Moraines.-The  wcstem  fi'out  of  tile  Wasatcli  is  determined 
by  a  great  fault.  From  the  line  of  this  fault  an  alluvial  plain  desci'uds 
westward  to  the  Jordan  River  and  Gi'eat  Salt  Lake,  wliile  eastward  springs 
a  steep  face  of  solid  rock,  the  escarpment  of  the  upthrown  orogenic  lilock. 

'  Quaternary  History  of  Mouo  Valley,  Califoruia,  by  I.  C.  Rutisull,  Eighth  Ann.  Kept.  U.  S.  Geol. 

.Snrvcy,  1881),  p.  :iOO. 


LITTLE  COTTONWOOD  CANYON  MORAINES.  307 

At  intervals  the  rock  face  is  divided  by  narrow  clefts  or  gateways,  whence 
streams  issue  from  the  interior  of  the  range.  Between  each  pair  of  adjacent 
streams  is  an  acute  ridge  of  rock,  whose  roof-like  cross-pi'ofile  marks  it  as 
the  product  of  acpieous  sculpture.  Tlie  end  of  each  is  truncated  by  the 
great  faidt,  and  the  truncated  terminals,  standing  in  line,  constitute  the 
rock  face  at  the  margin  of  the  plain.  The  plain  was  covered  by  the  water 
of  the  ancient  lake,  and  tlie  Bonneville  shore-line  is  scored  jiartl}'  on  tlic! 
alluvium  and  partly  <»n  the  tace  of  solid  rock.  Little  ( 'ottonwooil  Ciuiyon 
heads  in  the  liighest  part  of  the  range,  among  peaks  with  an  altitu<le  of 
12,000  feet,  and  after  a  curving  coui'su  of  twelve  miles  ends  at  the  rock  face 
in  a  gateway  wliose  threshold  is  slightly  lower  than  the  Bonneville  shore- 
line. The  glacier  which  anciently  followed  it  issued  from  the  gateway,  and 
at  its  maximum  development  encroached  upon  the  plain  about  one  mile, 
recording  its  position  at  various  stages  by  lateral,  frontal,  and  terminal 
moraines.  Within  the  throat  of  the  canyon,  scattered  erratics  are  the  only 
debris,  ])ut  immediately  outside  are  massive  lateral  moraines.  At  the  mouth 
of  the  canyon  its  walls  are  of  gray  quartzite,  which  in  weathering  assumes 
a  dark  brown  color,  but  in  the  heart  of  the  range  they  are  of  white  granite, 
and  the  morainal  debris  at  the  margin  of  the  ])l;iiu  is  nearly  all  granitic. 
This  contrasts  strongly  with  the  dark  (puirtzite,  and  enables  tlie  observer 
to  trace  out  the  distribution  of  the  erratics  from  a  single  commanding  posi- 
tion. The  lateral  moraine  at  the  south  is  of  typical  forni — an  acute  ridge 
of  granite  bowlders.  Where  it  joins  the  mountain,  its  crest  stands  340  feet 
above  the  flood  plain  of  tlie  creek;  but  it  falls  away  rapidly,  and  at  a  mile 
it  has  reached  the  level  of  tlie  plain,  beneath  which  it  sinks.  Before  disap- 
pearing, it  divides  into  four  or  tlve  members,  all  of  which  curve  toward  the 
axis  of  the  glacier  in  such  manner  as  to  indicate  that  they  were  the  lateral 
portions  of  successive  frontal  moraines.  Tlie  northern  or  right-hand  lateral 
moraine  is  of  a  very  different  type,  being  broad  and  flat-topped,  and  rising- 
only  about  100  feet  above  the  adjacent  flood-plain  of  the  creek.  Its  surface 
exhibits  fewer  bowlders  than  does  the  left  moraine;  and  a  fresh  section  at 
one  point  betrays  an  obscure  horizontal  arrangement  of  its  material.  Scat- 
tered bowlders  of  granite  are  to  be  seen  on  the  adjacent  wall  of  quartzite 
for  more  than  200  feet  above  it,  and  these  extend  northward  along  the 


308  LAKE  BONNEVILLE. 

mountain  side  for  half  a  mile  beyond  the  canyon.  Their  upper  limit 
becomes  gradually  lower  as  the  distance  from  the  canyon  increases. 

A  clearer  conception  of  these  relations  may  be  derived  by  consulting 
PL  XLII,  where  the  morainal  masses  are  colored  blue.  Tlicir  proper  inter- 
pretation appears  to  be,  that  after  the  glacier  had  built  two  lateral  inoriiines 
upon  the  phiin  in  tlie  usual  way,  it  expanded  t(»wanl  tlie  Udrtli,  overthrow- 
ing and  overflowing  the  moraine  on  that  side  and  destroying  its  character- 
istic form. 

The  plain  into  which  the  branches  of  the  southern  lateral  moraine  sink 
and  disappear  is  alluvial.  It  not  merely  surrounds  the  outsides  of  the 
moraines  but  occupies  the  space  between  them,  and  extends  up  the  canyon 
a  half  mile  or  more.  At  its  upper  limit  in  the  canyon,  the  creek  channel 
excavated  from  it  is  shallow,  but  its  depth  gradually  increases,  being  60 
feet  near  the  ends  of  the  moraines,  and  nearly  200  feet  at  a  point  two  or 
three  miles  beyond.  Where  the  greatest  section  is  exposed,  the  allm  ium 
has  a  depth  of  65  feet,  consisting  of  gravel,  coarse  and  fine,  with  a  prepon- 
derance of  granitic  pebbles  and  occasional  passages  of  sand.  Beneath  it,  is 
a  greater  depth  of  fine  sand,  laminated  and  ripple-marked,  and  abounding 
in  mica  flakes.  This  sand  is  evidently  a  subaqueous  deposit  and  records 
an  epoch  during  which  the  lake  stood  higher  than  the  Provo  shore-line. 
The  gravel  above  it  does  not  exhibit  the  cross  lamination  characteristic  of 
deltas,  and  must  be  classed  as  an  alluvial  deposit.  It  marks  a  time  when 
the  lake  stood  lower  than  the  Bonneville  shore-line,  and  is  prol)ably  refera- 
ble to  the  Provo  epoch.  To  establish  the  validity  of  this  reference,  an 
attempt  was  made  to  trace  the  alluvimn  continuously  to  tlu;  Pro\-o  shore- 
line, l)ut  this  was  frustrated  by  a  system  of  recent  displacements  A\liich 
traverse  the  plain  in  various  directions,  giving  rise  to  ti-rraces  which  can 
not  in  every  case  be  distinguished  from  the  stream  terraces  with  wliic-h  they 
are  associated.  After  making  all  allowance  for  displacements,  however, 
it  is  sufticiently  evident  that  when  the  ancient  alluvium  was  deposited, 
the  descent  of  the  stream  was  less  ra])id  than  at  present,  and  this  slo^\er 
descent  is  most  satisfactorily  accounted  for  by  assuming  a  barrier  of  lake 
water.  The  alluvium  is  therefore  referred  to  some  epoch  of  the  expanded 
lake. 


BIG  WILLOW  CREEK  MORAINES.  309 

The  next  canyon  to  the  southward  is  distinguished  from  Little  Cotton- 
wood Canyon  by  having  a  steep  grade  thi'oughout.  Instead  of  beginning 
in  the  recesses  of  the  range,  it  heads  upon  the  western  face  and  descends 
abruptly  to  the  plain.  At  its  lower  extremity  are  moraines  equally  massive 
with  those  of  Little  Cottonwood  Canyon.  They  include  two  lateral  moraines 
about  a  mile  in  length,  springing  from  the  angles  of  the  canyon  walls,  and 
iniiting  in  an  excejjtionally  heavy  terminal.  Just  within  the  mouth  of  the 
canyon  is  a  well-defined  frontal  moraine,  and  the  branching  of  the  laterals 
indicates  that  a  second  frontal  was  formed  between  this  and  the  terminal, 
but  has  been  buried  by  the  alluvium  accumulated  above  the  terminal.  The 
outflowing  stream.  Dry  Cottonwood  Creek,  has  indented  the  terminal,  but 
cascades  in  passing  it,  and  has  nuich  work  to  perform  before  it  will  have 
established  a  uniform  grade  through  it.  The  base  of  tlie  terminal  is  in  this 
case  not  ])uried  l)y  alluvium,  but  the  configuration  of  the  neig'hboring  plain 
suggests  that  it  may  once  have  been  partially  covered  and  afterward  denuded 
by  streams.  (See  PI.  XLII,  where  the  creek  is  erroneou.sly  called  "Big 
Cottonwood".) 

Two  miles  farther  south,  a  similar  high-grade  canyon,  whence  issues 
Big  Willow  Creek,  is  furnished  at  its  mouth  with  a  similar  moraine  system, 
of  which  the  terminal  is  the  most  conspicuous  element.  It  stands  free  upon 
the  surface,  with  no  evidence  of  an  alluvial  or  lacustrine  covering. 

The  alluvial  plain  does  not  at  all  points  reach  the  moiuitain  side  at  the 
same  altitude,  but  is  highest  at  the  mouths  of  the  large  canyons.  In  the 
vicinity  of  the  moraines,  its  highest  point  is  at  the  mouth  of  Little  Cotton- 
wood Canyon,  and  it  is  there  a  few  feet  above  the  horizon  of  the  Bonneville 
shore-line.  Elsewhere  the  shore-line  is  scored  upon  the  steep  mountain  front. 
It  is  to  be  seen  a  short  distance  north  of  the  northern  moraine  of  Little 
CottouAvood  Canj^on;  it  appears  again  between  the  moraines  of  Dry  Cot- 
tonwood and  Big  Willow  Canyons;  and  it  reappears  beyond  the  latter;  but 
no  trace  of  it  was  detected  upon  the  moraines  themselves.  In  the  case  of 
the  Little  Cottonwood  moraines,  the  alluvial  cover  prevents  examination  at 
the  horizon  of  the  shore-line;  but  the  other  moraines  are  fully  exposed  to 
view. 


310  LAKE  BONNEVILLE. 

Before  attempting-  tlie  interpretation  of  tlusse  glacial  plienoinena,  it 
will  be  well  to  recite  again  the  lacustrine  history  \\  itli  w  hich  tlie}-  are  to  he 
compared.  Lake  Bonneville^  was  twict;  foriiuMl  and  twice  dried  away.  It 
attained  its  maxinuim  size  during-  its  second  term,  and  the  records  of  the 
second  rising  so  far  mask  and  obliterate  the  records  of  the  first,  that  these 
are  discovcirable  at  comparatively  few  j)oints.  The  shore-line  oljserved  in 
the  vicinity  of  the  moraines,  and  the  alluvial  and  lacustral  deposits  ex))osed 
on  the  banks  of  Little  Cottonwood  Creek,  all  licloiig  inupiestionably  to  tlie 
second  Bonneville  epoch,  and  that  e|)och  ah  me  can  we  hope  to  compare 
with  the  epoch  of  the  moraines.  When  the  lake  reached  the  horizon  of  the 
Bonneville  shore-line,  during  its  second  rising-,  it  found  outlet,  and  its  fur- 
ther rise  was  jirevented.  The  erosion  of  the  barrier  was  exceedingly  rapid 
until  the  water  had  fallen  to  the  Provo  level.  The  resistance  of  this  lime- 
stone held  the  lake  at  a  constant  height  for  a  long-  period,  and  from  this 
level  the  w^ater  finally  receded  by  desiccation.  Had  the  rim  of  the  basin 
been  so  high  as  to  ])revent  outflow,  we  can  not  say  how  far  the  lake  would 
have  risen  before  the  passage  of  the  climatic  maximum  permitted  it  to  fall 
again.  We  may  be  siu-e,  however,  that  the  climatic  maximum  was  some- 
what later  than  the  epoch  of  the  Bonneville  shore-line,  (^n  the  other  hand, 
the  lake  area  at  the  Provo  stage  was  only  two-thirds  as  gi'eat  as  at  the 
Boinieville,  and  the  peculiar  climatic  changes  that  expanded  the  lake  were 
fast  declining  when  the  water  finally  fell  from  the  Provo  shore-line.  The 
climate  of  maximum  efficiency  for  the  production  of  lakes  therefore  occurred 
after  the  epoch  of  the  highest  shore-line  and  before  the  close  of  the  epoch  of 
the  Provo  shore-line. 

If  the  glaciers  had  attained  their  maximum  extent  either  during  or 
before  the  epoch  of  the  Bonneville  shore-line,  their  terminal  moraines  would 
have  been  subject  to  wave  action  at  that  horizon,  and  scored  with  shore 
marks;  but  the  tw'o  terminal  moraines  wdiich  are  well  exposed  to  view 
exhibit  no  .shore-lines.  If  the  glaciers  had  attained  their  maxinnnn  after  the 
close  of  the  Provo  epoch,  the  Little  Cottonwood  moraines  should  rest  upon 
the  alluvium,  instead  of  being  partially  buried  beneath  it.  It  apjiears  quite 
consistent  with  the  phenomena  to  suppose  that  the  ei)Och  of  maximum 
glaciation  was  covered  by  the  longer  epoch  of  the  Provo  shore-line.     The 


WASATCH  MORAINES  AND  LAKE  BONNEVILLE.  311 

j^reater  part  of  the  alluvium  outside  the  moraines  may  have  been  deposited 
while  they  were  in  process  of  formation,  the  inter-moraiiial  portion  being 
added  after  the  ice  had  retreated. 

We  are  thus  led  to  assign  the  same  narrow  time  limits  to  the  epoch  of 
the  climatic  maximum  tending  to  produce  lakes  and  to  the  epoch  of  the 
climatic  maxiimmi  producing  glaciers;  and  one  ftxrther  step  will  lead  us  to 
the  conclusion  that  the  two  maxima  are  identical.  But  before  taking  that 
step,  we  must  examine  the  evidence  from  the  Mono  Basin. 

Sierra-Mono  Moraines.-Tlie  Pleistoccne  lilstory  of  the  Mono  Basin  was  syste- 
matically investigated  by  Russell.  Oidy  a  few  days  were  spent  by  mo  in 
the  valley,  and  these  were  devoted  chiefly  to  the  features  described  in  the 
following  paragraphs.  In  preparing  these  paragraphs,  I  have  availed  myself 
of  Russell's  work  whei-ever  necessary,  but  the  local  descriptions  are  mostly 
at  first  hand.  The  reader  who  cares  to  pursue  further  the  history  of  the 
valley  will  find  it  fully  presented  in  Russell's  paper.^ 

Lake  Mono  has  an  altitude  of  6,730  feet.  When  expanded  by  the 
Pleistocene  climate,  it  carved  a  maximum  shore-line  670  feet  higher.  The 
eastern  face  of  the  Sierra  Nevada  is  here  remarkably  abrupt,  and  the  Pleis- 
tocene high-water  mark  runs  very  near  its  base.  In  glacial  times  the  broad 
back  of  the  Sierra  bore  a  great  field  of  ndvd,  the  surface  of  which  ranged 
in  altitude  from  10,000  to  12,000  feet.  From  this  streamed  glaciers  east 
and  west,  and  five  of  the  eastward-flowing  entered  the  Mono  basin.  One 
sto|)ped  before  reaching  the  level  of  the  old  shore-line,  the  other  four 
readied  it  or  passed  beyond  it.  These  will  be  enumerated  in  order  from 
north  to  south,  with  whatever  description  is  necessary  to  show  the  relation 
of  the  observed  glacial  phenomena  to  the  lacustral. 

The  Mill  Creek  glacier  emerges  from  its  rocky  channel  and  debouches 
upon  the  plain  at  the  horizon  of  the  old  shore-line.  Beyond  its  walls  of 
rock  its  dimensions  are  indicated  by  lateral  moraines,  which  rapidly  con- 
verge and  at  the  same  time  bend  northward.  They  are  steep-sided  ridges, 
studded  with  large  bowlders.  They  extend  less  than  a  mile  upon  the  plain, 
and  though  no  terminal  moraine  is  visible,  we  are  assured  by  their  converg- 
ence that  they  represent  the  full  length  of  the  glacier.     The  old  shore-line 

'Eighth  Ann.  Kept.,  U.  S.  Geol.  Surv.,  pp.  261-394. 


312  LAKE  BONNEVILLE. 

is  distinctly  marked  not  only  on  tlic  ontcr  lace  of  tlie  riglit  moraine  l)ut  on 
the  extremities  of  both,  and  for  a  sliort  distances  on  the  inner  faces  of  l)oth. 
Its  character  is  tliat  of  a  chtf  and  terrace,  Init  the  notch  is  not  deeply  cut, 
and  the  extremities  are  iKit  slightly  truncated. 

Seven  miles  farther  south  Lee\'ining  Creek  issues  from  the  mrmntain 
fjice  .at  ahout  tlie  altitude  of  the  old  shore-line.  The  modern  lake  is  there 
close  at  hand,  and  the  mountain  face  is  steep.  Upon  the  steep  slope,  the 
creek  has  l)uilt  a  large  alluvial  structiu-e  which  projects  a  cape  more  than  a 
mile  into  the  lake.  This  mass  of  alluvium  has  not  the  symmetrical  form  of 
an  alluvial  cone,  but  descends  somewhat  unequally  and  irregularly,  being 
evidently  a  comjjound  delta,  the  component  parts  of  which  were  formed  at 
different  levels  of  the  lake.  The  glacier  following  the  valley  of  this  creek 
had  for  several  miles  a  uniform  width  of  1^  miles,  and  this  width  was 
not  diminished  at  the  mouth  of  the  canyon.  Like  the  Mill  Creek  glacier, 
it  curved  northward  at  that  j)oint,  its  left  margin  following  the  flaring  mouth 
of  the  canyon,  while  its  right,  as  indicated  by  the  surviving  lateral  moraine, 
swung  free.  One  mile  ( )f  this  free  moraine  is  preserved,  but  no  terminal  is 
to  be  seen.  There  are,  however,  two  well  marked  frontal  moraines  King 
respectively  three-quarters  of  a  mile  and  two  miles  back  fiom  the  end  of 
the  lateral.  The  old  shore-line  is  scored  on  the  outside  and  inside  of  the 
lateral  moraine,  and  appears  also  on  the  ojiposite  side  of  the  glacial  channel 
against  the  face  of  the  mountain.  It  can  be  traced  only  a  short  distance 
uj)  the  glacier  valley,  because  its  features  have  been  i-ecently  obliterated 
by  the  creek.  The  end  of  the  moraine  has  evidently  been  cut  away  by  the 
waves,  but  the  extent  of  this  removal  is  unknown.  The  surviving  portion 
affords  no  indication,  by  size  or  direction,  that  the  end  of  the  glacier  was 
close  at  hand.  When  the  lake  stood  about  33  feet  lower  than  its  highest 
shore-line,  the  creek  built  a  small  delta  at  the  mouth  of  the  ghn'ial  Aalley, 
the  front  of  the  delta  reaching  to  the  end  of  the  truncated  lateral  7noraine. 
The  head  of  the  delta  was  at  the  foot  of  the  lower  frontal  moraine.  Near 
its  head  there  is  a  terrace  eight  feet  higher,  which  appears  to  be  a  fragment 
of  an  earHer  built  delta  that  was  destroyed  during  the  construction  of  the 
lower  one.     The  creek  channel  now  lies  entirely  below  these  delta  plains. 


MORAINES  OF  THE  MONO  BASIN.  313 

Tlie  next  glacier  descending  to  the  lake  level  issued  from  Bloody  Can- 
yon, six  miles  tarthei'  south,  and  at  the  time  of  its  greatest  development 
stretched  four  miles  upon  the  plain.  Its  position  on  the  plain  is  marked  by 
a  pair  of  lateral  moraines,  which  gradiially  converge  as  they  descend  the 
slo].:)e.  From  lioneath  the  right  member  of  this  pair  issue  the  extremities 
(»f  two  other  pairs,  marking  earlier  courses  of  the  same  glacier.  These 
older  moraines  do  not  rise  so  high  above  the  plain  as  those  later  formed,  and 
are  less  acute  in  profile.  They  have  evidently  been  subjected  to  atmos- 
pheric agencies  for  a  relatively  long  time,  and  it  seems  probable  not  only 
that  their  crests  have  been  worn  and  rounded,  l)ut  that  their  bases  have 
been  buried  by  the  slow  accumulation  of  alluvium.  The  waves  of  the 
ancient  lake  barely  reached  the  extremities  of  these  moraines,  older  and 
newer.  The  Hood  plain  of  the  streamlet  which  issues  from  between  the 
newer  moraines  coalesces  at  their  extremities  with  the  terrace  wrought  by 
the  waves,  so  that  we  cannot  say  in  this  case  whether  the  lake  water  entered 
the  valley  between  the  moraines.  The  moraines  end  in  low  sea  cliffs,  and 
there  is  no  terminal,  though  the  convergence  of  the  laterals  indicates  that 
the  ice  projected  a  little  farther.  That  a  terminal  properly  belongs  to  the 
system  seems  to  be  shown  by  a  series  of  frontals,  deposited  at  intervals 
farther  up  the  ice  channel. 

The  Rush  Creek  moraine  surpassed  all  the  others  in  size,  having  a 
width  of  1§  miles  where  it  entered  the  })lain.  Its  lateral  moraines  stand 
free  for  a  distance  of  three  miles,  and  each  one  is  characterized  by  several 
parallel  crests,  continuous  with  corresponding  frontals.  Three  frontals  of 
some  magnitude  follow  each  other  in  rapid  succession  near  the  end  of  the 
laterals.  The  position  of  the  terminal,  or  extreme  frontal,  is  not  certainly 
known.  The  old  shore-line  is  but  faintly  traced  in  this  portion  of  the  basin, 
where  it  margined  a  sliallow  bay,  l)ut  its  horizon  was  determined  to  fall 
near  the  base  of  the  outermost  frontal.  A  half  mile  farther  down  the 
slope  the  plain  is  interrupted  by  a  few  small  islands  of  morainal  matter, 
unmistakably  characterized  as  such  by  the  presence  of  gigantic  erratic 
bowlders.  These  mark  the  position  of  what  may  be  another  frontal  moraine, 
but  is  probably  the  terminal  moraine. 


314  LAKE  BONNEVILLE. 

Witli  one  voice  these  four  localities  tell  us  that  Mono  Lake  occupied 
its  maximum  level  after  the  glaciers  of  the  Sierra  had  retreated  from  their 
most  advanced  position.  But  their  testimony  goes  no  farther.  The  nar- 
row range  of  levels  connnon  to  the  two  niay  have  been  occupied  first  by 
the  ice  and  afterward  hy  the  water,  or  it  may  have  been  occupied  l)\  botJi 
tog(!ther.     We  can  oidy  say  tliat  the  ice  was  first  to  retreat. 

Combining  this  result  with  that  afforded  by  the  moraines  of  the  Bonne- 
ville Basin,  we  conclude  that  the  epoch  of  greatest  glaciers  fell  within  the 
second  period  of  lake  expansion,  but  did  not  coincide  with  the  ei)och  of 
greatest  watei'-supply;  it  occurred  somewhat  earlier.  If  the  two  sets  of 
phenomena  were  consequent  ujjon  the  same  series  of  climatic  changes,  then 
the  lacustral  changes  lagged  behind  the  glacial. 

That  such  a  lagging  admits  of  plausible  explanation  may  readily  be 
shown.  The  ncvd  and  glaciers  of  the  Mono  district  occupied  a  portion  of 
the  catchment  basin  of  the  lake.  The  preci})itation  which  they  accumulated 
during  their  growth  was  subtracted  from  the  precipitation  tributary  to  the 
lake,  and  the  same  was  afterward  returned  to  the  lake  when  they  were 
finally  iiielted.  Their  mass  of  ice  may  therefore  be  regarded  as  a  portion 
of  the  water-supply  of  the  lake,  arrested  in  its  progress.  When  the  climatic 
conditions  were  favorable  for  the  growth  of  lake  and  glaciers,  the  growth 
of  the  glaciers  antagonized  and  delayed  the  growth  of  the  lake.  When  the 
climatic  conditions  favored  the  wasting  of  lake  and  glaciers,  the  waste  of 
the  glaciers  fed  the  lake  and  thus  antagonized  its  depletion.  The  ascend- 
ing and  descending  phases  of  the  lake  thus  fell  behind  the  corresponding 
phases  of  the  glaciers,  and  the  maxima  and  minima,  or  turning*  points,  Avere 
correspondingly  displaced. 

It  is  to  be  observed  that  this  explanation  is  quite  distinct  from  the 
theory,  alluded  to  by  Whitney,*  that  the  Pleistocene  lakes  were  the  secpiel 
of  the  Pleistocene  glaciers,  being  created  by  their  melting.  Such  a  relation 
is  quantitatively  impossible.  In  the  Mono  basin,  indeed,  the  mass  of  snow 
and  ice  upon  the  mountains  may  have  been  equal  to  the  \(ilume  of  Mater 
in  the  valley,  but  in  the  Lahontan  and  Bonneville  basins  it  was  far  too 
small.     King's  map  of  the  Pleistocene  glaciers  of  the  Bonneville  Basin  indi- 

'  The  Climatic  Changes  of  Later  Geological  Times,  p.  185. 


SIERKA  MORAINES  AND  LAKE  MONO.  315 

cates  a  superficial  extent  of  710  square  miles,  an  area  only  j^  as  large  as  the 
water  surface  of  Lake  Bonneville.  ( )ne  thousand  feet  is  a  liberal  estimate 
of  tlie  mean  depth  of  the  ice,  while  the  mciin  dcptli  of  Lake  Bonneville  was 
about  700  feet.  The  body  of  water  was  therefore  about  twenty  times 
larger  than  the  body  of  ice. 

The  evidence  from  the  moraines  is  thus  shown  to  be  consistent  with 
that  from  the  moUuscan  fauna,  and  they  jointly  confirm  the  presumption 
derived  from  the  recency  and  exceptional  nature  of  the  lakes  and  glaciers, 
that  the  two  phenomena  were  coordinate  and  synchronous  results  of  the 
same  climatic  changes.  The  correlation  of  the  phenomena,  originally  l)ased 
on  analogy  merely,  is  thus  sustained,  and  it  now  stands  on  a  surer  founda- 
tion. 

It  fi)llows  as  a  corollary  that  the  glacial  period  of  the  Sierra  Nevada, 
the  Wasatch,  and  other  mountains  of  the  western  United  States  was  divided 
into  two  ei)ochs  separated  by  an  interglacial  epoch;  and  this  has  not  been 
independently  shown.  The  bifurcation  of  the  Bloody  Canyon  moraines 
demonstrates  a  temporary  retreat  of  the  glaciers,  but  that  retreat  was  not 
necessarily  great.  The  following  explanation  of  the  bifurcation,  advanced 
by  Russell'  and  McGee^  appears  to  be  fully  sustained  l)y  the  phenomena. 
After  the  glacier  had  constructed  on  the  plain  its  oldest  pair  of  lateral 
moraines,  it  retreated  to  a  point  near  the  canyon,  and  there  deposited  a 
heavy  frontal  moraine.  Readvancing,  it  was  opposed  by  this  frontal,  and 
found  a  point  of  least  resistance  in  the  left  lateral  moraine,  wliich  in  each 
pair  is  lower  than  the  right.  Overriding  that,  and  finally  demolishing  it, 
it  took  a  new  course  upon  the  plain,  and  this  new  course  was  afterward 
modified  by  the  same  process,  the  obstructing  frontal  being  near  the 
extremity  of  the  laterals.  At  almost  any  point  in  the  history  thus  deduced 
from  the  moraines,  there  might  have  occurred  a  great  retreat  of  the  glaciers, 
involving  even  their  temporary  extinction,  without  the  production  of  any 
features  we  should  be  able  to  detect. 

■  Eighth  Ann.  Rept.  U.  S.  Geol.  Survey,  p.  357. 

''Meridional  deflection  of  ice  streams,  by  W.  J.  McGee,  Am.  Jour.  Sci.,  3d  Series,  vol.  29,  p.  386. 


316  LAKE  BONNEVILLE. 

SUMMARY  OP  CHAPTER. 

Tlie  Bonneville  Basin  originated  by  distortion  of  the  earth's  cnist,  and 
came  into  existence  long  before  the  Bonneville  epoch.  Little  is  known  of 
its  earliest  climatic  and  physical  conditions,  but  it  was  coinpaniti\ely  dry 
for  a  long  period  immediately  preceding  the  formation  of  the  great  lake. 
During  this  period,  alluvial  cones  were  formed  about  the  bases  of  all  its 
greater  mountain  ranges,  and  the  smaller  ranges  were  wholly  or  partly 
buried  by  valley  deposits.  The  valley  deposits  may  have  been  entirely 
alluvial,  but  were  probably  also  partly  lacustral,  the  lakes  being  oi'  small 
extent. 

There  followed  two  epochs  of  high  water,  Avith  an  interval  during 
which  the  basin  was  nearly  or  quite  empty.  The  first  of  these  epochs  was 
at  least  five  times  as  long  as  the  second.  The  second  scored  its  water 
mark  90  feet  higher  than  the  first,  and  would  have  encroached  still  farther 
on  the  basin  sides  had  it  not  been  checked  by  outflow.  During  the  epoch 
of  outflow,  the  discharging  current  eroded  the  rim,  and  thus  lowered  the 
lake  375  feet;  and  after  the  outflow  had  ceased,  the  Avater  fell  by  desicca- 
tion, with  one  notable  interruption,  to  its  present  level  in  Great  Salt  Lake. 
The  inter-Bonneville  epoch  of  low  water  was  of  greater  duration  than  the 
time  that  has  elapsed  since  the  final  desiccation. 

The  final  drj-ing  of  the  basin  divided  it  into  ten  or  twelve  independent 
interior  basins.  Two  of  these  now  contain  lakes,  the  others  for  the  most 
part  contain  playas,  or  playa  lakes  wdth  beds  of  salt.  The  Sevier  Basin  is 
exceptional  in  that  its  lake  was  30  miles  in  length  when  first  surveyed,  and 
has  since  disappeared,  the  water  of  its  tributary  stream  being  appropriated 
for  irrigation. 

Since  1845,  the  date  of  the  first  record,  the  surface  of  Great  Salt  Lake 
has  oscillated  through  a  range  of  10  feet,  reaching  maxinia  in  IS;').")  and 
1S73,  and  minima  in  1847-50  and  1861.  Since  iSTlt  there  lias  l)een  little 
change.  A  progressive  fall  in  the  future  is  indicated,  not  as  a  matter  of 
climate,  but  as  a  result  of  the  rapidly  increasing  utilization  of  tlie  tributary 
streams  for  the  pin'])oses  of  agriculture.  Tlie  changes  in  level  have  l)een 
associated  with  changes  in  area  and  vohune.  The  maximum  area  was 
about  25   per  cent,  gi'eater  than  tlie  mininunn,  and  the  maximum  volume 


CONCLUSIONS  ON  CORRELATION  OF  LAKES  AND  GLACIERS.  3 1 7 

about  75  per  cent.  The  salinity,  which  is  high,  has  varied  inversely  with 
the  volume,  and  the  predicted  decrease  in  volume  will  lead  to  tlie  preci})ita- 
tion  of  a  portion  of  the  mineral  contents. 

A  comparison  of  the  lake's  oscillations  with  the  meteorologic  record 
of  the  region  a])pears  to  show  that  the  height  of  the  lake  in  any  year  is  a 
cumulative  function  of  tlic  jirccipitation  during  preceding  years,  1)ut  estab- 
lishes no  relation  between  lake  oscillations  and  temperature  oscillations. 

The  modern  oscillations  of  lake  surface  are  exponents  of  the  ii'regular 
rhythm  of  climate  due  to  the  interaction  of  complex  conditions  otherwise 
constant.  The  great  oscillations  which  alternately  created  and  destroyed 
Lake  Bonneville  are  of  a  different  order,  and  require  for  their  explanation 
more  permanent  changes  of  conditions.  An  examination  of  the  topography 
of  the  liasin  shows  that  such  diversion  of  water-courses  and  other  local 
geographic  changes  as  may  possibly  have  occurred  are  inadequate  to 
account  for  the  rise  and  fall  of  the  lake.  The  history  of  the  Bonneville 
oscillations  is  moreover  closely  paralleled  by  that  of  the  Lahontan  oscilla- 
tions, and  it  is  believed  that  they  belong  to  a  series  of  climatic  changes 
affecting  not  only  these  two  basins  but  the  adjacent  subdivisions  of  the 
Great  Basin.  The  question  whether  the  lakes  are  phenomena  of  the  Pleisto- 
cene period,  their  expansion  being  wrought  by  the  same  climatic  factors 
which  enlarged  the  glaciers,  has  previously  been  answered  in  the  affirmative 
on  the  basis  of  certain  analogies.  A  review  of  these  analogies  indicates  that 
two  are  valid,  while  two  others  are  not.  The  common  recency  of  lakes  and 
glaciers,  as  indicated  by  the  freshness  of  the  vestiges,  affords  a  presunq)tion 
in  favor  of  their  identity  in  time,  and  a  forther  presumption  is  afforded 
by  the  fact  that  the  lacustral  and  glacial  phenomena  each  interrLq)ted  a 
series  of  events  of  a  different  character.  The  argument  from  the  parallelism 
of  the  lacustral  and  glacial  histories,  each  being  characterized  ))y  two  prin- 
cipal maxima,  is  weakened  l)y  the  fact  that  tlie  liighest  autliorities  on  the 
Pleistocene  period  are  not  agreed  in  regard  to  its  l)ipartition.  The  l)elief 
that  any  climatic  cause  competent  to  increase  glaciation  would  likewise 
increase  lakes  appears  on  analysis  to  be  ill-founded,  certain  possible  com- 
binations of  conditions  being  competent  to  cause  simultaneously  an  increase 
in  the  area  of  ice  and  a  decrease  in  the  area  of  water. 


318  LAKE  BONNEVILLE. 

The  discarded  arguments  from  analogy  are  replaced  by  other  argu- 
ments of  a  more  direct  and  satisfactory  nature. 

A  discussion  of  the  conditions  controlling  the  climate  of  the  western 
United  States  sliows  that  any  change  competent  to  increase  the  glaciers  on 
on  the  mountains  would  lower  the  temperature  of  the  lake  basin.s.  An 
appeal  may  therefore  be  made  to  the  fauna  of  the  lake  epoch  for  infonnatioii 
in  regard  to  climate.  Hie  manunals  give  no  intelligible  answer;  but  the 
fresh-water  mollusks  declare  by  their  dei)au}jeration  that  the  conditions  of 
life  were  then  less  favorable.  In  the  case  of  Lake  Lahontan,  and  in  the 
case  of  the  first  Lake  Bonneville,  the  unfavorable  condition  may  ])ossibly 
have  been  impurity  of  water;  but  the  second  Lake  Bonneville  was  freshened 
by  outflow,  and  the  dwarfing  of  its  mollusks  is  best  explained  by  low  tem- 
perature. 

The  moraines  of  three  Pleistocene  glaciers  descend  from  the  Wasatch 
]\Iountains  to  the  level  of  the  Bonneville  shoi-e-line;  the  moraines  of  four 
glaciers  descend  from  the  Sierra  Nevada  to  the  level  of  the  old  shwe-line  of 
Mono  Lake;  and  the  relations  of  these  moraines  to  the  shores  of  the  lakes 
and  the  associated  deposits  indicate  that  the  maximum  stage  of  the  lakes 
coincided  closely  with  the  epoch  of  maximum  glaciation. 

These  phenomena  sustain  the  theory  that  the  Pleistocene  lakes  of 
the  western  United  States  were  coincident  Avith  the  Pleistocene  glaciers  of 
the  same  district,  and  were  produced  by  the  same  climatic  changes.  It  fol- 
lows as  a  corollary  that  the  glacial  history  of  this  region  was  bipartite,  two 
maxima  of  glaciation  being  separated,  not  by  a  mere  variation  in  intensity, 
but  by  a  cessation  of  glaciation. 


CHAPTER   VII. 

LAKE  noNNEVILLE  AND  VOLCANIC  ERUPTION. 

Ill  this  chapter  it  is  proposed  to  show  the  relations,  and  especially  the 
chronologic  relations,  between  the  volcanic  history  and  the  lake  history  of 
the  Bonneville  Basin.  The  only  species  of  volcanic  rock  there  erupted 
during  or  near  the  Bonneville  period  is  basalt,  and  this  appears  to  have 
lieen  thrown  out  alike  before,  during,  and  since  the  lacustral  epochs.  The 
description  of  the  various  lava  fields  will  in  a  general  way  follow  the 
inverse  order  of  their  formation,  but  precedence  will  be  given  to  the  more 
typical  localities. 

Of  the  various  volcanic  districts  of  Utah,  that  which  is  most  interest- 
ing in  this  connection  occupies  the  eastern  portion  of  the  Sevier  Desert  in 
the  vicinity  of  the  towns  of  Holden,  Fillmore,  Corn  Creek,  Kanosh,  and 
Deseret.  The  Pavaiit  Range  there  forms  the  eastern  limit  of  the  desert 
plain,  and  is  itself  composed  of  uplifted  strata  ranging  in  age  from  Car- 
boniferous to  Tertiary.  The  volcanic  buttes  and  tables,  all  very  small  as 
compared  to  the  mountain  range,  rest  upon  the  open  plain,  at  distances 
varying  from  10  to  30  miles.  Nearest  to  Fillmore  is  the  Ice  Spring  lava 
held,  with  its  cluster  of  craters.  Just  south  of  it  are  the  Tabernacle  field 
and  crater.  Still  to  the  southward  and  10  miles  away  are  two  considerable 
buttes,  not  far  from  the  town  of  Kaiiosh,  and  west  of  these  lies  a  higii 
basaltic  table  several  miles  in  extent.  North  of  the  Ice  S})riiig  field  there 
is  a  continuous  volcanic  tract,  some  10  miles  in  extent,  for  the  most  part 
coincident  with  the  plain,  but  including  also  a  large  mesa  opposite  Holden, 
and  a  large  tuflP  cone,  Pavaiit  Butte.  West  of  this  tract  and  south  of  the 
town  of  Deseret  lies  a  basalt  table,  and  farther  south  stands  a  tuft"  cone, 
Dunderberg  Butte. 

310 


320  LAKE  BONKEVILLE. 

The  Ice  Spring-  craters,  the  Tabernacle  hiva  beds,  and  Pavant  liutte  were 
first  visited  by  the  writer  in  1872,  and  an  account  of  them  may  be  found 
in  the  report  of  the  Wheeler  Survey.^ 

ICE  SPRING  CRATERS  AND   LAVA   FIELD. 

I'he  lavas  of  tliis  locality  are  the  most  recent  within  the  BonneAalle 
area,  and  tlicir  phenomena  are  ty})ical  of  subaerial  eruption. 

The  craters  are  grouped  closely  together,  and  the  manner  in  which 
they  overlap  each  other,  as  well  as  their  relations  to  the  various  lava  fldws, 
demonstrate  that  they  were  formed  successively  rather  than  synchronousl}'. 
Three  only  are  preserved  entire,  but  frag-ments  of  nine  more  were  discov- 
ered, and  it  is  probable  that  the  denudation  of  the  locality  would  reveal 
beneath  the  accumulated  lava  and  scoriae  the  remains  of  numerous  others. 
Of  the  discovered  crater  rings  no  two  are  concentric.  Thei'e  have  been 
at  least  twelve  successive  eruptions,  through  as  many  independent  vents, 
within  a  radius  of  1500  feet,  and  none  of  these  eruptions  appear  to  have 
been  large.  It  would  seem  that  the  subjacent  terrane  opposes  so  little 
resistance  to  the  upward  progress  of  the  lava  that  a  new  opening  is  made 
more  easily  than  an  old  one  is  reopened  after  a  cessation  t)f  activity  has 
permitted  congelation  in  the  conduit.  The  immediately  subjacent  forma- 
tions are  in  this  case  probably  the  White  Marl,  the  Yellow  Clay,  and  other 
feebly  coherent  valley  deposits. 

The  dimensions  and  general  relations  of  the  craters  and  laxii  fields  will 
be  best  understood  if  the  reader  will  examine  Pis.  XXXV,  XXXVII  and 
XXXVIII  in  connectioirwith  the  followhig  description.  (  hw  of  the  largest 
of  the  scoria  hills  is  the  Crescent,  a  crater  fragment  showing  nearly  one- 
half  of  the  original  circle.  It  rises  2f)0  feet  above  its  eastern  base,  and 
tlu!  entire  crater  api)ears  to  have  had  a  diameter  of  2200  feet.  It  is  coiii- 
po.sed  of  scoriaceous  fragments,  in  the  main  loosely  aggregated,  but  in  part 
bound  together  by  harder  layers  which  appear  to  have  been  jjroduced  by 
sj)lashings  of  molten  lava  from  the  crater.  These  give  it  a  rude  concentric 
stratification,  in  the  main  inclined  outward,  parallel  with  the  outer  slo])e, 
but  also  inclined  inward  at  a  very  high  angle  conformable  with  the   inner 

'  Surveys  West  of  the  100th  Meridian,  vol.  3,  pp.  136-144. 


U  S. '3 KC LOGICAL    SURVEY 


liAJ^E  BONNEVILLE      PL.  XXXV 


MAPOF  A 

VOLCANIC  DISTKK  T, 

Near  Filicnore ,  Utah. . 


TopogrcLpKy 
BvA.L.Vi%l,ster  curd  K^.  Wheeler . 

Geology 
By  O.K.  Gilbert  aihrl  I.  CBu^seU  . 


Legend 


NL      A'eaer BcLsaTtif:  Lean 


ScoT-ux, 


PL       Brt^a itic Zitva  ofU'ovo 


Scortti. 


(^Hxi-erBasattic  Irtva. 


age 


flUler 


Hhvollte 


Tuff  and  •Srona. 


L       -Letci/strirt-eMrrls  cuhd  Sands 


(h-psurn 

(r\jhfifkroiis  Clay 
Gypsiun  S^md 
Crdcarfoiis  Tufa. 


.luliutt  hi<-n  \  Co.Lth 


Drawn  bv- 11  Tlmiupson 


..=-5-      ^'^^~'%\Kr 


:Htri.j;iliM&i:, 


MITER  AND  CRESCENT  CRATERS.  321 

slope.  One  end  of  the  Crescent  is  buried  beneath  a  lava  crater,  the  Miter, 
the  other  is  cut  off  by  a  stream  of  lava  flowing  from  the  same. 

The  Miter  is  perhaps  the  most  i-eceut  of  the  craters.  Nothing  over- 
laps it,  and  it  has  lost  nothing  by  erosion.  Apparently  the  only  change 
since  its  formation  has  been  a  cracking  away  of  fragments  from  its  harder 
components  and  the  accumulation  of  these  in  taluses.  Its  rim  is  nearly 
circular,  with  a  diameter  of  950  feet.  Its  highest  side,  on  the  east,  rises 
250  feet  above  its  outer  base  and  275  feet  above  the  central  depression. 
Its  history  has  involved  at  least  two  overflows.  After  it  had  reached  about 
its  present  size  the  lava  rose  within  it,  breached  its  north  side,  and  dis- 
charged. The  discharge  was  followed  by  explosive  eruption  and  the 
breach  was  repaired.  A  final  upwelling  found  escape  at  the  west  and 
trenched  the  rim  deeply  on  that  side.  The  northerly  sill  of  discharge  is 
120  feet  above  the  central  depression,  the  westerly  75  feet.  The  material 
is  identical  with  that  of  the  Crescent,  and  the  perfect  preservation  of  the 
cone  enables  the  imagination  to  picture  vividly  the  manner  of  its  forma- 
tion. Its  principal  constituent  is  scoriaceous  lava  in  angular  fragments. 
Over  the  surface  are  sprinkled  clots  of  similar  scoriaceous  material,  spongy 
within,  bulbous  Avithout,  and  coherent  to  the  angiilar  fragments  beneath 
them.  These  are  evidently  di'ops  spattered  from  the  molten  mass  below, 
and  retaining  their  plasticity  up  to  the  moment  of  striking,  so  that  they 
fitted  themselves  to  and  adhered  to  the  surfaces  against  which  they  fell. 
They  are  volcanic  bombs  whose  aerial  flight  was  too  short  to  pentiit  them 
to  harden. 

Between  the  Miter  and  the  Crescent  stands  a  low  cone,  resembling  the 
Miter  in  form,  but  only  400  feet  in  diameter.  It  is  composed  almost  exclu- 
sively of  angular  scoriae.  Six  fragments  of  craters  project  from  beneath 
the  talus  of  the  Miter  at  various  points,  another  lies  outside  the  Crescent, 
and  still  another  joins  the  inner  face  of  the  Crescent  to  the  small  crater  just 
mentioned.  A  circular  hole,  more  than  100  feet  in  diameter  and  40  or  50 
feet  deep,  is  doubtfully  classed  as  a  crater,  for  it  is  not  clear  that  matter  has 
been  ejected  from  it.  Its  interior  exhibits  only  fragments  fallen  from  its 
walls. 

MON  I 21 


322  LAKE  BONNEVILLE. 

Tlie  Terrace  crater  lies  just  south  of  the  Miter,  and  differs  from  the 
others  in  type.  Its  walls  are  for  the  most  part  low,  and  are  characterized  by  a 
gentle  outward  slope.  At  their  culminating-  point  they  are  scoriaceous,  but 
elsewhere  they  are  of  relatively  compact  lava,  with  a  nide  stratification,  as 
though  formed  by  the  addition  of  successive  sheets.  Its  fonnation  was  evi- 
dently attended  by  very  little  explosive  action,  and  there  is  some  ground 
for  believing  that  its  cavity  was  produced  by  the  refusion  of  scoriaceous 
matter,  the  product  of  some  earlier  eruption.  Its  outline  is  iiTegular,  with 
an  extreme  length  of  1100  feet  and  a  width  of  700  feet.  At  one  stage  in 
its  history  it  was  occupied  by  a  molten  lake  about  14  acres  in  extent,  and 
the  partial  congelation  of  the  surface  of  this  lake  left  a  teiTace  at  one 
margin.  Tlie  subsequent  history  of  the  crater  includes  the  formation  of 
four  narrower  terraces  at  lower  levels.  The  first  lowering  of  the  molten 
lake  appears  to  have  been  accomplished  by  the  bi'eaching  of  the  crater  wall 
at  the  south,  and  a  consequent  outflow.  The  subsequent  lowerings  were 
caused  by  the  retreat  of  the  lava  down  the  conduit  by  which  it  had  origi- 
nally entered  the  crater  from  beneath.  This  conduit  remains  open  and 
can  be  explored  for  25  feet,  when  progress  is  stopped  by  water.  It  is  a 
circular  tube  12  feet  in  diameter,  and  inclined  10  or  15  degrees  from  the 
vertical.  The  stony  arrested  drops  still  pendent  from  its  sides  testify  by 
their  small  diameter  to  the  high  fluidity  of  the  lava.  The  dejith  of  the  crater 
below  its  general  rim  is  2G0  feet,  below  the  sill  of  its  last  outflow  220  feet, 
and  below  the  scoriaceous  crag  that  overlooks  it  on  one  side  350  feet. 

Three  thousand  feet  to  the  west  of  the  above  craters  there  is  a  short 
fragment  of  crater  wall,  with  its  concavity  turned  toward  the  east.  It  is 
nearly  buried  by  the  lava  streams  flowing  from  the  others,  but  what  remains 
in  view  indicates  a  diameter  of  half  a  mile.  It  bars  the  i)rogress  of  the  lava 
in  that  direction  and  helps  to  give  to  the  outline  of  the  field  its  bi-lobed  form. 

The  streams  flowing  from  these  craters  have  formed  two  confluent 
fields,  the  first  extending  3.5  miles  northward,  with  a  general  breadth  of  two 
miles,  the  second  3.25  miles  westwai-d,  with  a  general  breadth  of  1..")  miles. 
Their  area  is  about  12.5  s([uare  miles.  Their  marginal  depths  will  average 
about  30  feet,  and  their  mean  depth  is  estimated  at  50  feet.  The  vohnne 
of  the  ejected  matei-ial  is  approximately  one-eighth  of  a  cubic  mile.     The 


n. 


-J 


o 

2 

H 
I 
m 

s 

H 


nf       y 


TEKRAOE  CliATEE.  323 

greater  part  of  this  lava  is  nearly  compact,  dark  gray  in  fracture,  and  black 
on  the  suiiace.  The  fields  are  everywhere  exceedingly  rough,  correspond- 
ing to  the  "aa"  of  the  Sandwich  Island  nomenclature.^  The  surface  is  a 
heap  of  ragged,  loose  blocks,  piled  in  tumultuous  waves  whose  crests  are 
20  to  30  feet  above  their  troughs.  Near  the  craters  these  rugosities  of  sur- 
face disappear,  and  the  compact  basalt  is  covered  to  an  unknown  depth  by 
a  spongy  layer  as  light  as  the  lapilli,  but  more  even  in  texture,  and  main- 
taining the  somber  hue  of  the  streams.  The  scorice.  of  the  craters  is  some- 
times gray,  but  is  more  commonly  red  or  yellow.  At  a  few  points  on  the 
surfaces  of  the  streams  are  small  patches  of  scoria?,  colored  like  the  craters, 
and  one  of  these  which  was  examined  has  a  conical  form,  suggestive  of  for- 
mation in  situ  by  eruption  from  the  body  of  the  stream.  It  is  possible, 
however,  that  it  is  merely  a  fragment  of  a  fixed  crater  that  was  floated  off. 

The  angle  of  flow  was  not  measured,  but  is  certainly  small.  In  the 
vicinity  of  the  craters  the  grade  is  conspicuous  to  the  eye,  and  the  lava 
must  be  tliere  one  or  two  hundred  feet  higher  than  at  the  margin  of  the 
field.  All  of  the  later  streams  appear  near  the  craters  to  flow  in  channels 
depressed  fifteen  to  twenty  feet  below  adjacent  surfaces,  and  yet  these 
adjacent  surfaces  resemble  very  closely  the  surfaces  of  the  streams.  The 
explanation  ap])ears  to  be  that  each  of  these  outpourings  varied  in  volume, 
now  swelling,  now  shrinking.  When  most  copious  it  spread  beyond  its 
channel  like  an  aqueous  stream,  and  deposited,  not  its  sediment,  but  its 
crust.     The  walls  of  the  channels  display  a  confirmatory  stratification. 

That  the  entire  history  of  the  lava  field  is  post-Bonneville,  admits  of 
no  question.  It  lies  within  the  area  of  the  lake  at  so  low  an  altitude  that 
no  point  of  the  craters  reaches  to  the  level  of  the  Bonneville  shore-line,  while 
the  marginal  portions  of  the  stream  are  below  the  level  of  the  Provo  shore- 
line. But  the  craters  show  no  trace  of  wave  work,  and  on  the  surfaces  of 
the  lava  streams  no  lacustrine  sediments  appear.  The  lake  beds  surround 
the  lava,  but  neither  rise  toward  it  nor  rest  against  it.  A  local  fault,  which 
is  seen  in  one  place  to  have  displaced  the  Bonneville  White  Marl,  disap- 
pears beneath  the  lava  field  in  such  a  way  as  to  show  that  the  latter  was 
subsequently  spread. 

'  H.awaiian  Volcanoes,  by  Capt.  C.  E.  Diitton :  Fourth  Ann.  Rept.  U.  S.  Geol,  Survey,  p.  95. 


324  LAKE  BONNEVILLE. 

At  various  points  there  crop  out  from  beneath  the  Ice  Spring  field 
margins  of  an  older  lava  or  lavas,  of  uncertain  date.  They  are  distinguished 
from  the  newer  by  the  weathering  of  their  surface,  which  has  partially  lost 
its  original  rugosity,  and  bears  patches  of  soil  so  as  to  supjiort  a  scanty 
growth  of  grass  and  bushes.  At  two  points  these  are  seen  to  be  displaced 
by  the  fault  above  referred  to,  and  at  one  place  a  bed  of  lava  passes  under 
an  exposure  of  the  White  Marl.  If  all  these  older  lavas  have  approximately 
the  same  date,  they  are  probably  older  than  the  BonncA-ille  shore-hne. 

While  the  recency  of  the  Ice  Spring  volcanoes  as  compared  to  the 
Provo  epoch  is  sufficiently  clear,  their  absolute  antiquity  is  a  matter  of 
doubt.  The  state  of  preservation  of  the  latest  ejecta  is  fairly  to  be  com- 
pared Avith  that  of  similar  material  produced  by  Vesuvius  two  or  three 
centuries  ago,  but  the  mineralogic  differences  between  the  two  lavas  and 
the  climatic  contrast  between  the  two  localities  may  determine  very  different 
rates  of  disintegration.  At  the  Utah  locality  disintegration  has  produced 
no  soil  even  in  crevices.  A  study  of  the  surface  details  of  the  more  com- 
pact lava  gives  the  impression  that  they  have  withstood  atmospheric  influ- 
ences. The  scoriae  have  yielded  somewhat;  in  their  original  constitution 
they  consist  within  of  thin  septa  dividing  spheroidal  bubbles,  and  without 
of  a  slightly  thicker  skin  against  which  the  outer  phalanx  of  bubbles  are 
flattened.  From  the  scoriaceous  crusts  of  streams  near  their  sources  this 
skin  has  chiefly  disappeared.  It  is  well  preserved  only  on  the  brinks  of 
the  cinder  cones,  and  not  on  all  of  those.  After  my  first  visit  to  the  locality, 
I  exhibited  to  the  American  Association  for  the  Advancement  of  Science  a 
bomb  from  the  Miter  crater,  and  stated  that  its  skin  had  been  exposed  to 
the  elements  since  the  time  of  its  formation.^  A  more  careful  examination 
on  the  ground  has  satisfied  me  that  I  was  wrong.  The  taluses  on  its  outer 
and  inner  slopes  show  that  the  crest  of  the  crater  is  slowly  breaking  away, 
so  that  the  bombs  to  be  seen  near  the  crest  may  have  been  until  recently 
covered  and  protected  by  lapilli. 

I  discovered  no  accumulation  of  fine  fragments  from  the  disintegi-a- 
tion  of  scorite.  They  have  been  absorbed  by  the  crevices  and  the  surface 
remains  clean.     Indeed  the  formation  of  a  soil  is  indefinitely  postponed  by 

'  Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  23,  1875,  p.art  2,  p.  :!0. 


KECENCT  OF  ERUPTION.  325 

the  necessity  to  first  fill  the  all-pervading  crevices  of  the  cinder  cones  and 
the  aa.  Only  on  the  cindery  crusts  of  streams  near  the  craters  has  a 
beginning  been  made.  This  is  not  apparent  on  the  surface,  but  when  the 
rock-froth  is  broken  into,  its  inner  cells  are  found  half  filled  with  an  exceed- 
ingly fine  cream-colored  dust — evidently  an  eolian  deposit.  A  few  sage 
bushes  have  discovered  this  and  established  themselves.  No  minerals  were 
seen  in  the  bubbles  or  other  cavities,  but  the  interior  of  the  flue  of  the  Ter- 
race crater  is  decorated  with  dendi'itic  growths  of  calcareous  matter. 

The  name  of  the  Ice  Spring  lava  beds  is  derived  from  what  may  be 
regarded  as  a  natural  ice  house,  existing  in  one  of  the  deeper  hollows  of 
the  aa.  It  is  in  a  natural  pit  among  the  lava  blocks,  and  so  sheltered  by 
an  overhanging  ledge  that  it  never  receives  the  direct  rays  of  the  sun.  At 
the  time  of  my  visit  there  was  a  pool  of  ice  water  a  few  inches  broad  and 
half  an  inch  deep,  and  at  its  margin,  clinging  to  the  rock,  a  film  of  ice  a  few 
inches  across.  My  visit  was  on  September  28,  and  it  is  currently  reported 
that  ice  can  always  be  found.  The  conditions  of  the  phenomenon  appear 
to  be:  first,  the  accumulation  in  the  crevices  of  the  shattered  rock  of  cold 
water  from  melting  snow;  second,  protection  from  solar  heating-  by  means 
of  a  heavy  cover  conducting  heat  poorly;  third,  shelter  against  winds, 
which  would  bring  warmth  by  convection ;  and  fourth,  evaporation.  Simi- 
lar phenomena  have  been  described  at  various  places  in  the  Appalachian 
Mountains. 

PAVANT  BUTTE. 

Pavant  Butte,  which  stands  ten  miles  north  from  the  Ice  Spring  lava 
field  and  17  miles  by  road  from  Fillmore,  is  an  acute  peak,  about  800  feet 
high.  It  is  the  tallest  of  all  the  volcanic  hills,  and,  standing  alone  upon  the 
plain,  is  a  conspicuous  landmark.  Its  general  fonn  is  that  of  a  cratered 
cone,  but  the  crater  is  open  at  the  south,  and  the  circling  crest  has  an  acute 
culmination  at  the  north. 

Its  material  is  a  volcanic  tuff";  that  is  to  say,  it  consists  of  light  lapilli 
cemented  into  a  coherent  mass.  The  vesicles  of  the  lapilli  are  not  filled, 
but  the  fragments  are  so  firmly  held  together  that  they  are  frequently 
broken  across  when  the  mass  is  fractured.  Scattered  through  the  mass  are 
occasional  bowlders  of  basalt,  some  angular,  others  rounded,  and  these 


326  LAKE  BONNEVILLE. 

must  have  reached  their  position  })y  ejection  from  the  vent,  but  nothing 
was  seen  that  coukl  be  called  a  bomb,  and  none  of  the  scoria;  appear  to 
have  fallen  in  a  plastic  condition.  All  of  the  scoriaceous  matter  is  frag- 
mental,  and  the  fragments  rarely  exceed  an  inch  in  chameter.  Considerable 
portions  of  the  outer  slope  have  the  fineness  of  coarse  sand.  The  prevail- 
ing color  is  a  pale  yellow,  liut  some  of  the  weathered  surfaces  are  gray. 
In  this  respect  the  butte  is  strongly  contrasted  with  the  cinder  cones  of  the 
Ice  Spring  locality,  where  deep  colors,  especially  red  and  reddisli  broAvn, 
predominate. 

It  has  been  pointed  out  by  students  of  existing  volcanoes  that  lapilli 
are  cemented  into  tutf  when  their  deposition  takes  place  in  the  presence  of 
water.  This  commonly  happens  when  they  are  ejected  so  as  to  fall  in  water, 
or  when  heavy  rains,  accompanying  the  eruption,  wash  them  down  to  neigh- 
boring lowlands  in  the  form  of  volcanic  mud.  In  the  present  instance  the 
state  of  flowing  mud  was  not  reached,  for  they  are  heaped  about  the  vent 
in  steeply-inclined  layers  of  original  deposition.  The  associated  lake  phe- 
nomena suggest,  and  indeed  demonstrate,  that  Lake  Bonne\'ille  afforded 
the  moisture  necessary  for  cementation,  and  that  the  eruption  was  subaque- 
ous. Tlie  Bonneville  shore-line  is  trenchantly  drawn  about  the  sides  of  the 
butte  at  mid-height.  The  Provo  shore-line  appears  at  its  base,  and  the  inter- 
val is  destitute  of  all  trace  of  wave  action.  It  will  be  remembered  that  in 
the  order  of  time  the  Intermediate  shore-lines  were  formed  first,  then  the 
Bonneville,  and  finally  the  Provo.  The  presence  here  of  the  Boime\nlle 
and  Provo  traces  shows  that  the  butte  was  not  built  after  the  epocli  »>f  the 
Bonneville  shore-line.  The  absence  of  Intermediate  shores  tells  us  that  it 
was  completed  after  their  date.  A  portion  of  the  mole  may  have  been 
thrown  up  in  the  earlier  part  of  the  second  lake  epoch  or  at  any  previous 
time,  but  if  so,  it  was  completely  buried  by  the  product  of  the  final  eruption 
at  the  time  of  the  Bonneville  shore-line. 

This  determination  of  date  de])ends  on  our  knowledge  of  the  shore- 
line history  derived  from  other  localities,  but  the  same  information  may  be 
obtained  from  data  purely  local.  At  numerous  points  on  the  north  side  there 
is  exhibited  an  unconformity  in  the  bedding  of  the  tufa,  and  a  study  of  this 
unconformity  shows  that  after  the  waves  liiul  notched  the  profile  on  tluit 


PAVANT  BUTTE. 


327 


side,  producing  a  sea-cliff  and  a  terrace,  the  renewal  of  eruption  partially 
filled  the  notch,  the  newer  layers  dipping  at  a  higher  angle  than  the  old. 

We  thus  learn  by  consistent  and  cumu- 
lative evidence  that  an  eruption  took  place 
here  while  Lake  Bonneville  was  at  its  liio'h- 

o 

est  stage,  and  beneath  a  body  of  water  350 
feet  deep.  The  resulting  cone  was  built  not 
only  to  the  surface  of  the  water  biit  450  feet 

'^  Fig.  37.— IMa^am  to  illustrate  the  Alter- 

higher.     Eruption  ceased  with   the  fall   of    °''«<"'  "f  voicauic  Eruption  and  Littorai  Ero 

^  ■*■  aion  on  Pavaut  Butte. 

the  water  and  has  not  been  resumed. 

Notwithstanding  the  recency  of  the  cone,  its  sides  are  conspicuously 
furrowed  by  erosion,  and  it  is  in  that  respect  contrasted  with  most  frag- 
mental  volcanic  cones  of  the  vicinity.  Where  the  lapilli  are  uncemented, 
all  rain  is  swallowed  by  the  interstices,  and  escapes  gradually  and  quietly 
at  the  base.  On  Pavant  Butte  this  is  prevented  by  the  cement,  and  the 
rain  flows  down  the  surface,  accomplishing  its  usual  work  of  erosion.  The 
sides  of  the  furrows  exhibit  to  some  extent  the  internal  structure  of  the 
mass,  and  show  it  to  be  a  fine  type  of  its  kind.  There  ai'e  no  partings 
between  the  layers  of  tuff,  but  lines  of  deposition  are  plainly  to  be  seen,  and 
these  exhibit  on  the  inner  side  a  dip  toward  the  crater  at  35  degrees,  and 
on  the  outer  face  an  opposite  dijj  of  from  15  to  25  degrees,  the  two  systems 

being  joined  along  the  crest  by 
anticlinal  curves.  A  figure  illus- 
trating this  arrangement  is  here 
reproduced  from  the  Wheeler 
report  (Fig.  38). 

The  general  distribution  of  yellow  and  gi'ay  colors  indicates  that  the 
yellow  is  original  and  the  gray  a  result  of  weathering.  The  sections 
exposed  by  recent  erosion  show  the  main  mass  to  be  yellow,  but  there  are 
occasional  thin  bands  of  gray,  and  these  are  inferred  to  record  the  temporary 
cessation  of  eruption.  The  old  sea-cliff  against  which  the  newer  tuff  rests 
unconformably  does  not  show  the  gray  color,  a  fact  consonant  with  our 
belief  that  the  latest  eruption  interrupted  rather  than  followed  the  destruc- 
tive work  of  the  Bonneville  waves. 


Fig.  38.— Section  of   Pavant  Butte.     O=0at8ide  of  Crater. 
/^Inside  of  Crater.    B=Bonneville  shore-line. 


328 


LAKE  BONNEVILLE. 


•v^--  - 


-  ^,-  /■ 


iXwr 


Fir,.  39.— Section  at  base  of  Pavant  Bntte,  showing  Eeninant  of 
earlier  Tuff  Cone.  The  dotted  lines  indicate  theoretic  sMiictnre  of  parts 
concealed  or  removed. 


From  the  northwestern  base  there  jut  a  number  of  ragged  spurs,  con- 
sisting, like  the  main  mass,  of  tuff,  but  exhibiting  dips  toward  tlic  liill  instead 
of  from  it.  A  study  of  their  dips  shows  that  the  spurs  are  remnants  of  an 
older  crater  rim,  on  whose  ruins  the  surviving  rim  was  built.  The  diagram, 
Fig.  39,  shows  by  full  lines  the  observed  relation  of  dijjs,  and  Ij}-  dotted 

lines  the  theoretic  structure 
of  the  parts  concealed  or  re- 
moved. The  earlier  crater 
was  somewhat  smaller  than 
the  later,  and  its  center  was 
forther  noi-tli.  Tlie  tuff  ex- 
hibits, throughout,  the  gray 
color  referred  to  weathering.  The  date  of  the  structure  is  uncertain.  Its 
tuffaceous^  character  indicates  subaqueous  eruption.  Its  color  suggests 
prolonged  exposure  to  the  atmosphere  after  the  chief  work  of  demolition 
was  perfonned.  It  may  have  been  built  during  the  earlier  part  of  the 
epoch  of  the  "WHiite  Marl,  while  the  oscillating  lake  Avas  beginning  the  for- 
mation of  the  Intermediate  shore-lines,  or  still  earlier  in  the  epoch  of  the 
Yellow  Clay. 

The  surface  of  the  plain  for  a  short  distance  in  all  directions  from  the 
cone  is  composed  of  debris  derived  from  it.  Beyond  this  southward  outcrops 
the  White  Marl,  and  beneath  the  White  Marl  a  field  of  lava.  The  White 
Marl  seems  to  be  but  two  or  tln-ee  feet  thick,  and  as  there  appears  no  reason 
why  the  open  plain  at  this  point  should  not  receive  the  full  deposit,  it  is 
inferred  that  only  the  upper  portion  is  visible,  the  lower  being  beneath  the 
lava.  As  the  Bonneville  and  Proro  shore-lines  are  contemporaneous  with 
the  upper  portion  of  the  Marl,  the  question  arises  whether  the  lava  bed  may 
not  be  contemporaneous  with  the  later  tuff,  and  derived  from  the  same  vent. 
The  surface  of  the  lava  is  as  perfectly  preserved  as  that  of  the  Ice  Spring 
field,  but  is  of  an  entirely  different  type,  corresponding  to  tlie  pahoehoe  of 
the  Sandwich  Islands.     It  exhibits  fine  examples  of  the  curved  convolutions 

'  Tufa  and  tuff,  etyinologically  the  same  word,  have  both  been  used  to  designate  a  calcareous 
deposit  from  solntioii  ami  alHO  a  cohcront  aggregate  of  lapilli.  Following  GiMkie,  I  have  in  the.se 
pages  allotted  the  two  words  in  .wveralty  to  the  two  functions,  applying  tnfa  and  tu/aceous  to  the 
deposit  from  .solntion.  ami  luff -.mil  tuffaceoua  to  the  volcanic  product. 


ERUPTION  BENEATH  LAKE  BONNEVILLE.         329 

or  wi-inkles  that  are  so  suggestive  of  coils  of  rope.  At  the  time  of  my  exam- 
iuatiou  I  was  disposed  to  refer  these  to  the  inter-Bonneville  dry  epoch,  for 
it  appeared  to  me  a  priori  that  a  lava  stream  flowing  beneath  the  water 
would  part  with  its  heat  so  rapidly  that  its  smooth  sui'face  would  be  shat- 
tered into  fragments.  But  I  am  informed  by  Captain  Button  that  where 
Hawaiian  lava  streams  of  the  smooth  type  have  entered  the  sea,  their  surface 
characters  have  not  been  affected.  The  evidence  comprised  in  the  thinness 
of  the  White  Marl  and  the  perfect  preservation  of  the  lava  surface  beneath 
it  may  therefore  be  accepted  as  showing  that  a  lava  was  here  spread  under 
the  water  during  the  second  lacustrine  epoch ;  and  the  close  association  of 
the  field  with  the  Pavant  tuff  is  probable.  Its  area  is  undetermined,  for  it 
is  overlain  not  only  by  the  marl,  but  also  in  places  by  a  belt  of  sand  dunes. 
In  a  southwesterly  direction  it  is  visible  at  intervals  for  several  miles. 

TABERNACLE  CRATER  AND   LAVA   FIELD. 

The  typical  phenomena  of  the  Ice  Spring  and  Pavant  localities  simplify 
the  interpretation  of  the  Tabernacle  eruptions.  The  Tabernacle  field  lies 
immediately  south  of  the  Ice  Spring,  and  is  mapped  on  PL  XXXV.  It  is 
approximately  circular,  with  an  average  diameter  of  tlu-ee  miles  and  an  area 
of  about  seven  square  miles.  The  point  of  issue  is  not  central  biit  lies  near 
the  southeast  margin. 

The  crater  has  two  rims,  an  outer  and  an  inner.  The  outer  rim  is  the 
older  and  is  composed  chiefly  of  yellow  tuff.  It  contains  also  some  slag- 
like material  colored  dark  red  and  grey.  Its  contours,  which  are  in  detail 
the  result  of  weathering,  are  smooth,  except  where  broken  by  slaggy  crags. 
Its  surface  is  largely  composed  of  discrete  lapilli,  just  beneath  which  the 
tuff  may  be  found  in  place.  Two-thirds  of  the  original  annulus  is  preserved, 
the  part  toward  the  northwest  having  been  absorbed  or  buried  by  later 
eruptions.  The  span  of  the  annulus  from  crest  to  crest  is  2200  feet,  and  the 
ridge  is  highest  on  the  east  side,  where  it  rises  120  feet  above  the  lava  field. 
Probably  a  part  of  its  base  is  concealed  by  the  lava.  Its  profile  as  seen 
from  the  Miter  crater  (PI.  XXXIX)  resembles  the  Mormon  Tabernacle  at 
Salt  Lake  City,  sug'gesting  an  appropriate  name.  The  internal  structure  of 
the  ridge  is  not  well  displayed,  but  an  outward  dip  was  observed  in  the 
higher  part. 


330  LAKE  BONNEVILLE. 

The  inner  rim  is  characterized  by  a  great  abundance  of  scoriaceous 
matter  that  evidently  reached  its  position  while  still  pasty  and  adhesive.  It 
is  not  greatly  inflated,  and  its  general  habit  is  rather  slaggy  than  scoria- 
ceous.    The  rim  is  exceedingly  uneven,  and  abounds  in  rough  pinnacles. 

Comparing  these  features  with  those  of  Pavant  and  the  Ice  S[)ring 
craters,  we  infer  with  confidence  that  water  was  present  in  the  crater  during 
the  greater  part  of  the  formation  of  the  outer  rim  and  was  absent  dm'ing 
the  formation  of  the  inner  rim. 

When  compact  hand  specimens  of  the  Tabernacle  and  Ice  Spring  lavas 
are  compared,  little  difference  is  seen,  but  their  streams  differ  widely  in 
habit.  The  Tabernacle  field,  though  by  no  means  smooth,  is  far  less  rugged 
than  the  Ice  Spring.  Some  of  the  surface  is  broken  into  blocks,  which  are 
so  far  displaced  that  they  are  not  easily  traversed  on  horseback ;  but  the 
greater  part  is  comparatively  even,  and  exhibits  the  ropy  structure  charac- 
teristic of  pahoehoe.  A  conspicuous  character  of  the  streams  was  the  con- 
gelation of  their  upper  portions  and  the  subsequent  escape  of  the  liquid 
matter  beneath.  This  is  shown  in  a  few  places  by  the  preservation  of  tubu- 
lar caves,  and  more  frequently  by  depressed  areas,  where  the  lava  crust  has 
manifestly  settled  down  as  its  support  was  withdrawn.  The  constituent 
streams  of  the  field  are  partially  separable,  and  the  latest  may  be  traced  to 
the  inner  rim  of  the  crater. 

At  its  outer  margin  the  lava  field  terminates  in  most  directions  in  a 
cliff — not  such  a  cliff  as  results  from  the  undercutting'  of  a  lava  bed  resting 
on  softer  material,  but  a  cliff  of  original  formation  contemporaneous  with 
the  upper  surface.  At  a  point  on  the  eastern  side  it  was  measured  and 
found  to  have  a  height  of  65  feet. 

On  the  face  of  this  cliff,  near  the  top,  is  a  ])and  of  calcareous  tufii 
adhering  to  the  Ijasalt,  and  above  it  there  was  detected  at  some  points  a 
terrace  of  wave  erosion.  These  are  features  of  the  Provo  shore-line.  The 
crater  rims  Ijear  no  trace  of  wave  work,  and  this  negative  evidence  is 
reinforced  by  the  absence  of  all  lacustrine  deposits  from  the  crater,  from 
the  general  surface  of  the  field,  and  from  the  sunken  areas  and  caves.  The 
inner  rim  and  tlie  field  were  never  sul>merged;  the  outer  may  possibly  have 
been  covered  at  the  epoch  of  the  Bonneville  shore,  but  not  at  that  of  the 
Intermediate  shores. 


THE  TABEENACLE.  331 

Lying  just  above  the  Provo  level,  and  yet  showing  no  trace  of  sub- 
mergence, the  lava  field  must  have  been  formed  after  the  tall  of  the  water 
from  the  Bonneville  level  to  the  Provo.  Bearing  the  Provo  shore  mark,  it 
must  have  been  spread  before  the  close  of  the  Provo  epoch.  It  therefore 
originated  during  the  Provo  epoch.  The  inner  rim  of  the  crater  has  the 
same  date.  The  outer  rim  is  older  than  the  inner  and  younger  than  the 
Intermediate  shores;  it  belongs  to  the  Bonneville  shore  epoch  or  to  the 
earlier  part  of  the  Provo  epoch.  The  presence  in  it  of  some  slaggy  matter 
suggests  irregularity  in  the  supply  of  water  and  indicates  the  later  date. 
The  most  probable  history  is  as  follows:  When  the  Pleistocene  lake  fell  to 
the  Provo  level,  it  had  a  depth  of  from  fifty  to  seventy-five  feet  over  the 
present  site  of  these  craters  and  lava  fields,  and  there  it  remained  for  many 
centm'ies.  An  eruption  occurred  beneath  its  surface.  At  fii'st,  or  at  least 
during  an  early  stage,  the  eruption  was  explosive,  its  violence,  possibly 
stimulated  by  the  water,  being  so  great  that  the  circle  of  maximum  deposit 
was  more  than  a  thousand  feet  from  the  vent.  Eventually  the  growing 
rampart  shut  out  the  water,  the  explosions  becaine  less  violent,  and  the 
ejecta  became  pasty.  Quiet  eruption  followed,  developing  a  low,  black 
island,  which  received  a  wave  record  before  the  final  desiccation.  The 
closing  phase  of  eruption  was  explosive. 

The  geologic  date  of  this  lava  field  is  so  well  determined  that  special 
interest  attaches  to  the  degree  of  freshness  of  its  surface.  Decay  has  pro- 
gressed far  enough  to  obliterate  the  finer  convolutions  and  somewhat  obscure 
the  coarser — two  to  six  inches  across.  Probably  salient  parts  have  yielded 
an  inch  to  atmospheric  waste.  The  minor  depressions  contain  an  inch  or 
two  of  soil,  and  small  cracks  are  filled.  Large  cracks  remain  open.  Judged 
by  its  color,  the  soil  is  less  the  product  of  local  disintegration  than  of  eolian 
deposition.  The  principal  vegetation  is  the  common  sage  of  the  country. 
In  the  caves  the  eolian  deposit,  reinforced  by  the  di'oppings  of  bats  and 
probably  other  animals,  has  a  depth  of  one  or  two  feet. 

The  ground  just  north  of  the  Tabernacle  field  is  traversed  by  a  fault, 
with  a  throw  of  fifteen  or  twenty  feet  to  the  west.  It  divides  the  lava,  also, 
and  was  traced  with  diminishing  throw  half  way  to  the  crater.  In  the 
opposite  direction  it  disappears  at  the  edge  of  the  Ice  Spring  field,  being 
overplaced  by  that  eru2:)tion. 


332  LAKE  BONNEVILLE. 

At  the  side  of  the  fauh  is  a  k)w  hill  of  scoriae,  against  and  around 
which  the  Tabernacle  lava  flowed.  It  is  a  vestige,  ill  preserved,  of  some 
long  anterior  bnt  dateless  eruption.  Another  vestige,  equally  vague  as  to 
time,  appears  in  an  inclined  fragment  of  a  basalt  sheet,  brought  up  l)y  a 
fault  at  the  south  margin  of  the  Tabernacle  field.  This  fault  is  overplaced 
by  the  Tabernacle  lava. 

PLEISTOCENE  WINDS. 

The  circular  wall  of  a  crater  often  grows  more  rapidly  on  one  side 
than  another.  This  must  sometimes  be  occasioned  by  the  obliquity  of  the 
flue,  but  observers  have  generally  refen-ed  it  to  the  deflection  of  flying 
fragments  by  the  wind.  If  a  group  of  extinct  craters  are  oriented  in  the 
same  way,  it  seems  legitimate  to  infer  the  prevailing  dhection  of  the  wind 
at  the  time  of  their  formation.  In  the  Fillmore  district  there  is  practical 
harmony  of  orientation.  The  Crescent,  the  Miter,  and  the  smaller  crater 
between  them  have  their  highest  walls  at  the  east.  That  of  the  Terrace 
crater  is  at  the  northeast.  The  outer  rim  of  the  Tabernacle  culminates 
on  the  east  side,  the  inner  rim  on  the  north.  The  apex  of  Pavaiit  Butte 
stands  north  of  the  crater.  The  entire  range  of  the  seven  is  from  north  to 
east,  and  the  indication  is  that  winds  from  the  south,  southwest,  and  west 
prevailed.  There  are  no  meteorologic  stations  competent  to  tell  us  whence 
the  winds  blow  at  the  present  time,  but  the  prevailing  air  movement  is 
recorded  by  nature  in  a  satisfactory  manner.  In  the  vicinity  of  George's 
Ranch,  at  the  south  end  of  the  eastern  lobe  of  the  Sevier  Desert,  the  Provo 
shore-line  consists  of  a  series  of  massive  bay  bars,  composed  largely  of  sand. 
These  are  the  source  of  a  broad  train  of  dunes  which  traverse  the  desert, 
and  which  demonstrate  by  their  northeasterly  course  the  prevalence  of 
southwesterly  winds.  The  phenomena  consist  with  the  theory  that  the  gen- 
eral air  cun-ents  of  this  region  during  the  Pleistocene  were  similar  in  du-ec- 
tion  to  those  of  the  present  time. 

FUMAROLE  BUTTE  AND  LAVA  FIELD. 

The  most  important  locality  remaining  to  be  described  is  at  the  north- 
ern edge  of  the  Sevier  Desert,  close  to  the  head  of  the  Old  River  Bed.  A 
basaltic  mesa  five  miles  across  in  either  direction  is  half  divided  by  a  valley 


FUMAROLE  BDTTE.  333 

opening  to  the  northeast.  (See  PI.  XXXI,  near  bottom.)  At  its  head  this 
valley  is  a  mile  wide,  and  is  floored  by  red  scoriae.  In  it  stands  a  rough 
tower  about  160  feet  high  with  a  truncated  and  obscurely  crateriform  sum- 
mit. The  predominant  colors  of  the  tower  are  red  and  gray,  and  its  material 
ranges  from  firm  scoriae  to  compact  basalt.  These  are  roughly  bedded, 
and  exhibit  a  centi-ipetal  dip  at  a  high  angle.  The  inten-elations  of  these 
featm-es  are  easily  understood,  at  least  in  a  general  Avay.  The  tower,  Fu- 
marole  Butte,  marks  the  position  of  the  volcanic  vent.  About  this  vent 
scoriae  were  piled  (as  restored  in  the  diagram)  in  an  annular  mole,  and 
from  it  escaped  the  lava  of  the  surrounding  mesa.  The  last  phase  of 
erujition  was  non-explosive,  and  compact  rock  was  fonned  in  the  flue. 
Subsequent  erosion  carried  away  much  of  the  scoriaceous  rim,  but  left  the 
resistant  core  and  the  equally  resistant  lava  field. 


c .: e^— 


Fig.  40.— Theoretic  section  of  Fumarole  Butte.    The  Cinder  Cone  is  restored  by  dotted  lines. 

Before  visiting  this  butte  I  had  listened  with  incredulous  interest  to 
the  statement  that  smoke  or  steam  Avas  sometimes  seen  to  rise  from  it,  but 
personal  observation  subsequently  removed  all  doubt.  About  the  outer 
edge  of  the  summit  are  thirty  or  forty  crevices  from  which  wann,  moist  air 
gently  flows.  The  permanence  of  the  phenomenon  is  attested  by  the  ver- 
dure lining  the  openings — a  deep  green  moss  glistening  with  moisture  and 
vividly  contrasting  alike  with  the  somber  rocks  and  the  sparse,  ashen  vege- 
tation without.  In  diff"erent  openings  I  found  the  temperatures  62°,  70°, 
72°,  and  73.5°  Fahr.,  all  above  the  atmospheric  mean  for  the  locality,  which 
is  approximately  55°.  At  the  time  of  observation  the  outer  air  had  a  tem- 
peratui-e  of  30°,  and  was  dry.  A  little  mist  formed  over  some  of  the  open- 
ings, but  was  reevaporated  within  a  few  feet.  On  days  that  are  moist,  cool 
and  still,  a  conspicuous  cloud  must  arise.  It  can  hardly  be  doubted  that  this 
thermal  manifestation  testifies  to  a  residuum  of  volcanic  heat  in  the  old  flue. 

A  group  of  hot  springs  at  the  southeastern  base  of  the  mesa  may  have 
the  same  significance.     Their  temperatures  range  from  110°  to  178°  Fahr. 


334  LAKE  BONNEVILLE. 

Just  north  of  the  mesa  is  a  basaltic  hill  whose  apex  overlooks  the  mesa 
and  has  about  the  height  of  the  butte.  This  hill  is  terraced  l)y  wave  action, 
exhibiting  especially  the  Bonneville  and  Provo  shores.  Tlie  Bonneville 
terrace  appears  also  about  thirty  feet  above  the  base  of  the  butte,  and  a 
single  point  of  the  mesa  was  high  enough  to  receive  it. .  The  I'elation  of 
these  shore  benches  to  the  valley  about  the  butte  shows  clearly  that  the 
excavation  of  the  valley  was  antecedent  and  was  subaerial.  The  littoral 
excavation  was  trivial  in  comparison. 

The  wet-weather  di-ainage  of  the  mesa  crosses  its  liounding  cliff  at 
numerous  points,  and  at  each  of  these  a  narrow,  notch-like  valley  has  been 
eroded  from  the  basalt.  These  notches  were  cut  before  the  Bonneville 
epoch,  and  during  that  epoch  were  partly  filled  by  lake  deposits.  Subse- 
quent erosion  has  not  wholly  removed  these  deposits,  and  the  remnants 
show  that  both  Yellow  Clay  and  White  Marl  were  present. 

These  facts  demonstrate  that  not  only  the  volcanic  eruption  but  the 
principal  erosion  of  the  volcanic  formations  took  place  in  Tertiary  time. 

The  surface  of  the  mesa  has  lost  all  details  of  its  original  configuration. 
One  can  not  say  whether  the  flowing  lava  assumed  the  rough  or  the  smooth 
type.  It  is  far  from  smooth,  but  its  unevenness  apparently  depends  on  ine- 
quality of  disintegration  and  erosion.  The  rock  is  superficially  red  from 
decomposition,  and  is  generally  bare  of  soil,  the  slopes  of  surface  sufficing 
for  the  rapid  removal  of  disintegrated  material.  The  margins  of  the  table 
on  the  east  and  south  (where  alone  they  were  examined)  are  cliffs  by  sap- 
ping— that  is  to  say,  blocks  of  rock  have  fallen  away  in  consequence  of  the 
yielding  of  a  softer  substratum.  Probably  the  lava  was  spread  on  the  plain 
before  the  first  establishment  of  drainage  on  the  line  of  the  Old  River  Bed. 
The  carving  of  that  channel  lowered  the  base  level  of  erosion  for  the  i-egion 
and  induced  the  general  degradation  of  the  plain,  so  that  the  field  of  obdu- 
rate basalt  became  a  hill  of  circumdenudatiou.  The  greater  share  of  this 
process  also  must  be  referred  to  the  Tertiary. 

The  most  impressive  phenomenon  of  the  locality  is  the  secular  persist- 
ence of  the  volcanic  heat.  At  the  time  of  eruption  the  rocks  adjacent  to 
the  conduit  or  conduits  became  heated,  and  the  lava  remaining  in  dikes  and 
chimneys  added  to  the  store  of  heat.    Since  that  time  conduction  has  steadily 


U  S.OEOLOOrOAL    SUFA'EY 


layj:  bci'Inkvjll:-:    fl  xli 


Juliu»  Itirn  ft  Co.Iiih 


Dt-nMn  bj-  C  ThoippBon 


ANCIENT  CRATER  STILL  WARM. 


335 


carried  this  lieat  in  all  directions,  and  the  convection  of  snbterranean  water 
has  helped  to  discharge  it  to  tlie  atmosphere,  and  yet  enough  remains  to 
sustain  a  fumarole  ten  centigrade  degrees  warmer  than  the  air.  The  period 
of  heat  dissipation  includes  the  whole  of  the  Pleistocene  period  and  an 
antecedent  period  of  erosion  probably  of  equal  length. 

OTHER    LOCALITIES  OF  BASALT. 

The  remaining  basaltic  masses  of  the  lake  area,  so  far  as  they  were 
inspected,  do  not  declare  their  age  by  visible  phenomena  of  superposition, 
])ut  tlie  majority  can  be  referred  with  probability  to  the  Tertiary  from  a 
comparison  of  their  condition  of  preservation  with  that  of  the  Tabernacle 
field  oil  the  one  hand  and  the  Fumarole  on  the  other.  This  statement 
applies  to  all  localities  mapped  in  PI.  XLI  north  of  the  fortietli  parallel 
excepting  that  on  Bear  River.  It  applies  also  to  two  localities  at  the  west 
edge  of  the  Sevier  body  of  the  lake,  to  two  near  Preuss  Bay,  to  two  which 
trench  on  Escalante  Bay,  to  the  buttes  near  Corn  Creek  (southwest  of  Fill- 
moi'e)  and  a  large  table  west  of  them,  and  to  a  table  lying  west  of  Pavant 
Butte  and  south  of  the  town  of  Deseret. 


Fig.  41— Duuckrburg  Butte. 


3:!6  LAKE  BONNEVILLE. 

Between  this  last-named  table  and  the  north  end  of  the  Beaver  Creek 
range  stands  Dunderberg  Butte,  the  remnant  of  what  may  have  been 
a  large  cone  of  scorioe.  Its  lapilli  are  coherent,  Init  have  not  the  yellow 
color  of  the  tuff  cones.  Their  mass  is  traversed  by  dikes  and  .sheets  of 
vesicular  liasalt.  Some  of  the  basalt  vesicles  contain  calcite  and  zeolitic 
minerals.  The  top  is  flat,  except  where  dikes  project,  having  been  trun- 
cated by  the  waves  at  the  Provo  epoch.  The  date  of  eruption  can  be 
judged  only  from  the  progress  of  demolition.  It  was  probably  Tertiary, 
but  may  have  been  inter-Bonneville. 

Equally  in  doubt  are  a  basaltic  table  north  of  Pavant  Butte  and  another 
south  of  it  and  extending  nearly  to  the  Ice  Spring  field. 

PLEISTOCENE  ERUPTIONS  ELSEWHERE. 

The  same  criteria  of  discrimination  may  be  a})plied  with  equal  pro- 
priety outside  the  lake  area,  so  far  as  the  conditions  of  rock  decay  are  sim- 
ilar. Carefully  applied,  they  would  serve  to  classify  the  greater  number  of 
basaltic  eruptions  of  the  Arid  Region  as  severally  Tertiary  or  Pleistocene. 
While  engaged  in  general  geologic  exploration,  I  have  seen  in  Utah,  Idaho, 
Nevada,  California,  Aiizona  and  New  Mexico  about  two  hundred  fields  of 
lava,  judged  by  their  color  and  habit  to  be  basaltic,  and  as  many  as  tlu-ee 
hundred  and  fifty  cones  of  basaltic  scoria?.  My  attention  was  usually  not 
called  to  their  state  of  preservation,  but  the  data  contained  in  note  books 
and  memory  nevertheless  afford  a  basis  for  judgment,  and  I  have  attempted 
a  classification,  with  the  following  result:  Of  the  streams  and  fields,  15 
per  cent,  are  judged  to  be  Pleistocene;  of  the  cones,  60  per  cent.;  the 
remainder  are  regarded  as  Tertiary.  Of  the  eruptions  thus  classed  as 
Pleistocene  a  certain  number  admit  of  no  question,  and  these  are  enumer- 
ated in  the  following  paragraph. 

On  the  Markaguut  Plateau  in  southern  Utah,  close  to  its  western  edge, 
are  three  or  more  lava  fields  of  the  rougher  type,  all  fresher  in  apjDearance 
than  the  Tabernacle  field,  and  ^vith  them  are  ten  or  twelve  cinder  cones, 
red  and  black.  It  is  said  that  Panguitch  Lake,  a  few  miles  towai-d  tlie 
northeast,  owes  its  existence  to  the  danaming  of  its  valley  by  a  lava  stream 
nearly  as  fresh.     On  the  face  of  the  cliff  which  bounds  the  Pownsagunt 


PLEISTOCENE  ERUPTIONS.  337 

Plateau  on  the  south,  a  cinder  cone  marks  the  position  of  a  vent  from  which 
a  black  stream  has  flowed  down  the  slope  toward  the  valley  of  Kanab 
Creek.  This  stream  has  weathered  somewhat  more  than  has  the  Tabernacle 
lava,  but  recency  is  indicated  by  the  small  amount  of  subsequent  erosion  in 
a  country  whose  whole  configuration  indicates  rapid  degradation.  In  the 
heart  of  the  Uinkaret  Mountains  of  northern  Arizona,  surrounded  by  scores 
of  basaltic  streams  and  craters,  the  majority  of  which  are  probably  Ter- 
tiary, there  is  one  field  of  intense  blackness  rivaling  the  Ice  Spring  field  in 
freshness.  South  of  the  Grand  Canyon  of  the  Colorado  there  is  a  similar 
forest  of  cratered  cones  about  the  base  of  San  Francisco  Mountain,  and  as 
one  surveys  them  from  that  peak,  his  eye  is  arrested  by  a  lava  field  at  the 
east  on  which  vegetation  has  not  yet  encroached,  and  by  several  craters 
near  it  of  exceptional  jJerfection.  On  the  source  of  the  San  Jose  in  New 
Mexico  a  stream  of  lava  preserves  the  wrinkles  of  viscous  flow,  and  its 
siu'face  has  scarcely  yielded  to  the  corrasion  of  a  brooklet  that  crosses  it. 
At  the  southwestern  base  of  the  Zuili  Plateau,  near  El  Moro,  is "  a  long-, 
broad  lava  stream,  comparable  in  age  with  the  Tabernacle  field.  In,  south- 
eastern California,  on  the  grand  alluvial  cones  of  the  eastern  front  of  the 
High  Sierra  there  are  a  dozen  bright  red  and  black  cinder  cones  marking 
vents  whence  basalt  has  descended  toward  Owen's  River.  Farther  north, 
in  the  same  structural  meridian,  a  small  basaltic  mass  overlies  one  of  the 
glacial  moraines  of  Mono  Valley. 

RHYOLITE.  ' 

Besides  basalt,  the  only  important  volcanic  rock  of  the  Bonneville 
area  is  rhyolite.  It  stands  next  also  in  point  of  recency,  Ijut  is  far  older 
than  Lake  Bonneville.  So  far  as  observation  extended,  its  most  recent 
example  is  a  body  lying  just  east  of  Coyote  Spring,  at  the  south  end  of  the 
Sevier  Desert.  This  had  an  original  depth  of  three  hundred  feet  or  more, 
and  an  extent  in  each  direction  of  several  miles;  but  it  has  been  so  dis- 
sected by  erosion  along  its  lines  of  drainage  that  its  original  configuration 
is  suggested  rather  than  shown.  Its  system  of  valleys  has  a  general  depth 
of  at  least  two  hundred  feet,  and  these  are  so  related  to  the  Bonneville 
shore-line  as  to  show  their  earlier  formation. 

MON  I 22 


338  LAKE  BONNEVILLE. 

Just  east  of  the  Tabernacle  lava  field  is  a  liill  of  <,n-ey  rhyolite  one  or 
two  hundred  feet  high.  It  is  a  worn  remnant,  with  nothing  in  its  a.spect  to 
aid  conjecture  as  to  its  original  extent.  Its  Ijase  is  concealed  by  the  lake 
beds,  and  its  sides  show  terracing  by  the  waves  of  Provo  and  Intermediate 
times.  Lying  to  the  leeward  of  a  gy^isum  playa,  it  has  acqviired  a  white 
mantle  of  gypseous  sand  dunes,  whence  it  is  called  "White  Mountain"  (see 
page  223  and  PI.  XXXY). 

A  portion  of  the  Dug  way  range,  on  the  south  margin  of  the  Great 
Salt  Lake  Desert,  is  of  rhyolite  and  rhyolitic  tuff.  It  is  of  such  antiquity 
that  the  original  shapes  due  to  eruption  have  been  replaced  by  those  of 
atmospheric  sculpture.  From  its  gorges,  as  from  other  mountain  gorges, 
there  are  spread  great  fans  of  alluvium,  and  across  these  completed  fans 
are  traced  the  shore-lines  of  Bonneville. 

SUMMARY  AND  CONCLUSIONS. 

The  extravasation  of  rhyolite  in  the  immediate  vicinity  of  Lake  Bonne- 
ville was  long  anterior  to  the  epoch  of  the  lake.  The  same  may  be  said 
of  the'  earlier  extravasations  of  basalt,  but  the  period  of  basaltic  erujjtion 
includes  the  period  of  lake  extension.  In  the  Fillmore  district  basalt  was 
extruded  at  various  times  during  the  epoch  of  the  White  Marl  (later  Pleis- 
tocene), and  from  one  vent  there  were  eruptions  after  the  final  desiccation 
(post-glacial). 

The  states  of  preservation  of  lava  beds  of  various  determined  epochs 
afford  a  rude  scale  for  the  chronologic  classification  of  lava  beds  not  other- 
wise correlated,  and  warrant  the  conclusion  that  in  Utah,  Nevada,  New 
Mexico,  Arizona,  and  California  the  majority  of  basalt  flows  are  Tertiary; 
a  small  minority  are  Pleistocene,  and  of  these  a  few  are  post-glacial.  The 
post-glacial  eruptions  are  found  in  each  of  the  indicated  States  and  Terri- 
tories except  Nevada,  and  belong  to  eight  distinct  volcanic  districts. 

Although  human  history  fails  to  give  satisfactory  record  of  the  occur- 
rence of  any  of  these  eruptions,  their  antiquity,  as  measiu'ed  in  years, 
can  not  be  great,  and  an  application  of  the  general  law  of  ])robabilities  leads 
us  to  look  forward  to  a  resumption  of  volcanic  activity.  The  subteiranean 
reaction  of  which  basaltic  extravasation  is  the  consequence  has  continued 


VOLCANIC   EPOCH  NOT  CLOSED.  339 

in  the  broad  region  not  only  tlirough  the  Pleistocene  but  through  a  much 
longer  period  of  preceding  time.  The  intermittence  of  eruption  doe-s  not 
argue  discontinuity  of  the  subterranean  process,  for,  whatever  that  process 
may  be,  it  involves  the  production  of  an  unstable  equilibrium  that  is  con- 
verted to  stable  equilibi-ium  only  by  eruption,  and  such  conversion  is 
always  rhythmic.  The  abrupt  cessation  of  a  process  so  widely  spread  and 
so  long  sustained  is  highly  improbable,  and  its  gradual  cessation  would 
naturally  include  not  only  growing  infrequency  of  eruption  l^ut  the  suc- 
cessive extinction  of  eruption  districts.  The  number  of  post-glacial  erup- 
tions and  the  number  of  districts  among  which  these  were  distributed  alike 
assure  us  that  the  end  is  not  yet. 

Their  distribution  in  time  and  space  indicates  that  the  volcanoes  and 
the  lakes  have  been  genetically  independent.  The  Fumarole  volcano  broke 
out  during  an  epoch  of  aridity,  long  before  the  first  expansion  of  the  lake; 
the  Pavant  and  the  Tabernacle  were  built  on  sublacustrine  foundations; 
the  Ice  Spring  volcanoes  continued  the  series  after  the  water  had  subsided. 
Outside  the  basin  there  was  a  parallel  volcanic  history,  and  though  the 
volcanic  districts  are  irregularly  disposed,  one  can  not  say  that  they  are 
either  more  or  less  abundant  in  the  vicinity  of  the  site  of  the  lake. 


CHAPTER    VIII. 

LAKE  BONNEVILLE  AND  DIASTROPIIISM. 

The  displacements  of  the  earth's  crust  which  produce  mountain  ridges 
are  called  orogenic.  For  the  broader  displacements  causing  continents  and 
plateaus,  ocean  beds  and  continental  basins,  our  language  affords  no  term 
of  equal  convenience.  Having  occasion  to  contrast  the  phenomena  of  the 
narrower  geographic  waves  with  those  of  the  broader  swells,  I  shall  take 
the  liberty  to  apply  to  the  broader  movements  the  adjective  epeirogenic, 
founding  the  term  on  the  Greek  word  tJTreipo?,  a  continent.  The  process 
of  mountain  formation  is  orogeny,  the  process  of  continent  formation  is 
epeirogeng,  and  the  two  collectively  are  diastrophism.^  It  may  be  that 
orogenic  and  epeirogenic  forces  and  processes  are  one,  but  so  long  at  least 
as  both  are  unknown  it  is  convenient  to  consider  them  separately. 

The  mountain  ranges  so  thickly  set  in  the  Bonneville  district,  and 
generally  in  the  Great  Basin,  are  orogenic  phenomena;  the  concavity  of 
the  Bonneville  Basin,  whereby  it  is  constituted  an  area  of  interior  drainage, 
is  epeirogenic.  Neither  process  of  displacement  belongs  exclusively  to  the 
remote  past,  but  both  are  associated  with  the  lake  history.  The  e\adence 
of  this  association  is  of  three  kinds,  consisting  (1)  of  the  phenomena  of 
faults,  (2)  of  departure  of  shore-lines  from  horizontality,  and  (3)  of  the 
anomalous  ])osition  of  Great  Salt  Lake. 

EVIDENCE  FROM  FAULTING ;  FAULT  SCARPS. 

In  the  district  of  the  Great  Basin  the  characteristic  structure  of  mount- 
ain ranges  is  one  in  which  faults  play  an  important  part.  Foldings  of 
strata  are  not  wanting,  but  the  greater  features  of  relief  appear  to  have 

'  Seo  iioto  on  page  3. 
340 


OROGENY  AND  EPEIROGENY.  341 

been  wrought  by  the  displacement  of  orographic  blocks  along  lines  of"  fault. 
Sometimes  a  mountain  range  consists  of  a  great  block  of  strata  cut  off  along 
one  side  by  a  profound  fault,  and  inclined  in  the  opposite  direction  until  it 
descends  beneath  the  plain  constituted  by  the  alluvial  deposits  of  the  adja- 
cent valley.  More  frequently  there  are  other  faults  within  the  range,  trend- 
ing parallel  to  its  length,  and  having  throws  on  the  same  side  with  the  throw 
of  the  greater  fault  at  the  base. 

It  was  probably  these  internal  faults  which  originally  suggested  the 
structure  of  the  ranges  as  faulted  orographic  blocks ;  but  the  structure  was 
soon  connected  with  a  certain  set  of  topographic  features,  and  came  to  be 
recognized  by  means  of  these.  A  range  consisting  of  a  faulted  block  gen- 
erally has  a  bold  front  on  the  side  of  the  fault,  and  is  less  abrupt  on  the 
opposite  slope.  On  the  side  of  the  bold  front  the  line  separating  the  rock 
of  the  mountain  from  the  alluvium  of  the  valley  is  simple  and  direct,  while 
on  the  opposite  side  it  is  tortuous.  On  the  side  of  the  fault  the  strata 
usually  dip  away  from  the  adjacent  valley;  on  the  opposite  side,  toward  it. 
It  was  not  until  after  the  structure  had  been  discovered  and  described  by 
several  geologists  that  the  more  decisive  evidence  afforded  by  the  fault 
scarp  was  brought  to  bear.  The  writer  first  became  aware  in  the  summer 
of  1876  that  lines  of  faulting  may  sometimes  be  traced  upon  the  ground  by 
means  of  low  cliffs  or  scarps  due  to  displacement  of  so  recent  date  that  the 
atmospheric  processes  of  sculpture  liave  not  yet  restored  the  ordinary  forms 
of  topographic  detail.  Since  that  time  he  has  observed  many  such  scarps 
in  various  parts  of  the  Bonneville  Basin,  and  in  other  portions  of  the  Great 
Basin,  and  the  observation  has  been  still  further  extended  by  others, 
especially  by  Russell.^ 

The  observed  fault  scarps  for  the  most  part  follow  the  outcrops  of  fault 
planes  whose  position  had  previously  been  inferred  from  the  configuration 
of  the  adjacent  mountains,  but  they  have  served  also  to  betray  a  number  of 
faults  whose  existence  might  otherwise  not  be  suspected.  An  illustration 
of  this  is  found  on  the  west  side  of  the  A([ui  range  of  mountains,  where 
the  strata  constituting  the  range  dip  down  apparently  beneath  the  allu\ium 

'  Fourth  Ann.  Kept.  U.  S.  Geol.  Survey,  pp.  445,  448,"  449, 452.  Geological  history  of  Lake  Lahon- 
tan,  Chap.  X. 


342  LAKE  BONNEVILLE. 

of  Skull  viillcv.  The  typical  aspcft  of  the  faulted  mountain  front  is  here 
wanting,  and  the  actual  fault,  demonstrated  by  a  superficial  scarp,  naturally 
escaped  the  attention  of  the  geologists  who  have  described  and  ligured  the 
structure  of  the  range. 

A  case  of  more  frecpient  occurrence  is  that  in  which  the  fault  along  the 
base  of  the  range  is  compound,  one  portion  following  the  visible  edge  of 
the  rock,  and  another  portion  lying  some  furlongs  or  even  some  miles  val- 
ley-ward. The  orogenic  block  between  the  two  fault  planes  lies  far  lower 
than  the  one  constituting  the  mountain  range,  and  may  be  far  higher  than 
the  one  beneath  the  valley.  Occasionally  some  portion  of  it  is  visible,  but 
it  is  usually  completely  buried  by  the  alluvium  constituting  the  foot  slope 
of  the  mountain,  so  that  the  surface  affords  no  intimation  of  its  existence, 
unless  some  recent  faulting  records  the  position  of  its  margin  l)y  a  scarp. 

It  was  at  the  base  of  the  Wasatch  Range  that  the  fault  scarj)  was  iirst 
discriminated  as  a  distinct  toi)ographic  feature,  and  up  to  the  jjresent  time 
that  range  has  afforded  the  best  illustrations.  A  descrij)tion  of  the  phe- 
nomena there  exhibited  will  now  be  given  somewhat  in  detail,  following 
the  order  from  south  to  north.  It  should  be  premised  that  the  fault  scarps 
were  at  no  time  a  leading  subject  of  investigation;  the  region  was  traversed 
upon  other  errands,  and  the  faults  were  obser\ed  incidentally.  The  record 
therefore,  although  involving  much  detail,  is  far  from  full  or  exhaustive. 

The  Wasatch  Range,  using  the  term  in  the  most  restricted  sense,  may 
be  said  to  extend  from  the  town  of  Nephi,  near  which  it  culminates  in  Mount 
Nebo,  northward  to  the  Gate  of  the  ]leav  River,  where  its  axis  is  ver\'  low. 
The  geireral  course  is  a  little  west  of  north,  and  there  are  two  angles  just 
north  of  ]\rount  Nebo,  which  have  the  effect  of  offsetting  the  axis  some 
miles  to  the  eastward.  Near  the  town  of  Santa(pnn  there  is  a  low  spur 
projecting  westward  and  continued  across  the  valley  in  a  line  of  hills. 
Forty  miles  farther  north  a  higher  spur,  kno\A-n  as  the  Tra\erse  Range,  runs 
westward.  A  third  spur  lies  just  north  of  Salt  Lake  City,  and  a  fourth  a 
few  miles  north  of  Ogden,  near  the  town  of  lionneville.  These  orographic 
features  and  tlic  i)()sitions  of  the  localities  described  in  the  following  para- 
grapli  can  be  lu'st  made  out  b\-  the  aid  of  the  large  map  ol  Lake  Bonne- 
ville. 


FAULT  SCARPS.  343 

From  Nephi  to  the  pass  near  Santaquin  the  range  is  lofty,  and  has  a 
rather  high  alluvial  foot  slope  toward  Juab  valley.  At  a  variable  distance 
from  the  mountain  base  this  foot  slope  is  traversed  by  a  fault  scarp  from 
ten  to  thirty  feet  in  height.  It  is  for  the  most  part  single,  l)ut  in  places  it  is 
divided  into  two  parts,  and  it  was  observed  at  several  points  to  fade  out, 
being  coincidently  replaced  by  a  similar  scarp  a  few  rods  up  or  down  the 
slope,  and  lapping  past  it.  Toward  the  north  it  swings  nearer  to  the  mount- 
ain base,  and  it  was  finally  seen  to  leave  the  valley  altogether  and  strike 
across  the  neck  of  the  Santaquin  spur.  Juab  Valley  lies  at  such  an  alti- 
tude that  the  water  of  Lake  Bonneville  covered  only  its  lowest  part,  and 
the  shore-lines  lie  far  lower  on  the  slope  than  the  fault  scarp.  There  is  thus 
no  direct  relation  establishing  the  order  of  sequence  of  the  lake  and  the 
displacements,  but  the  relative  recency  of  the  last  displacement  is  inferred 
from  the  state  of  preservation  of  the  scarp. 

Evidence  of  faulting  was  next  seen  in  the  ancient  deltas  on  the  Spanish 
Fork,  deltas  lying  in  the  reentrant  angle  produced  by  the  inflection  of  the 
mountain  axis  north  of  Mount  Nebo.  There  were  distinguished  two  deltas, 
synchronous  with  the  Bonne^^lle  and  Provo  shore-lines,  the  Bonneville  delta 
being  widely  trenched  by  erosion  and  containing  the  head  of  the  Pi'ovo 
between  its  surviving  segments.  The  fault  scarps  are  numerous,  producing 
a  confused  topography,  and  their  zone  is  at  least  a  mile  broad.  The  majority 
traverse  the  upper  delta  only,  and  the  abrupt  manner  in  which  certain 
scarps  terminate  at  the  edge  of  this  demonstrates  that  they  were  produced 
after  the  formation  of  the  upjier  delta  and  before  the  completion  of  the 
lower.  The  greatest  throw  of  a  single  fault  observed  on  the  upper  delta 
is  more  than  150  feet;  the  greatest  throw  on  the  lower  delta  is  about  40 
feet.  The  throw  of  all  the  faults  is  toward  the  went,  but  the  strips  of  delta 
plain  lying  between  the  parallel  faults  are  inclined  toward  the  east.  The  net 
displacement  was  evidently  such  as  to  increase  the  height  of  the  mountain 
with  reference  to  the  \-alley,  but  its  amount  was  not  ascertained.  Thence  to 
Hobble  Creek,  five  miles,  the  zone  of  displacement  follows  the  margin  of  the 
alluvial  slope  where  it  adjoins  the  mountain  face,  and  usually  includes  from 
two  to  half  a  dozen  fault  scarj^s.  These  in  the  main  trend  parallel  to  the 
base  of  the  mountain  range,  but  a  few  scarps  depart  from  it  at  high  angles. 


344  LAKE  BONNEVILLE. 

At  Hobble  Creek  the  fault  scarps  are  numerous,  and  tlicv  are  well 
exhibited  on  tlie  surface  of  the  Bonneville  delta.  Their  total  tln-ow  was 
estimated,  \\itli  the  aid  of  an  aneroid  barometer,  to  be  125  feet.  Their 
states  of  preservation  indicate  that  they  are  of  varifuis  dates,  and  the  latest 
formed  is  so  fresh  that  vegetation  has  not  yet  entirely  covered  its  slope. 
A  little  farther  north  a  fault  is  seen  to  traverse  a  beach  line  of  the  Inter- 
mediate series,  giving  the  contiguous  portions  of  the  l)eacli  a  difference  in 
altitude  of  about  thirty  feet. 

Near  the  city  of  Provo,  a  small  mountain  torrent  issues  from  a  gorge 
called  Rock  Canyon.  At  the  mouth  of  the  canyon  is  a  delta  terrace  at  the 
Bonneville  level,  with  a  radius  of  about  1,700  feet,  and  divided  midway  by 
the  stream.  The  stream  has  opened  a  passage  several  hundi'ed  feet  broad, 
and  is  flanked  on  one  side  by  a  stream  teirace.  The  greater  portion  of  the 
delta  terrace  on  both  sides  of  the  stream  is  corrugated  by  faulting,  being 
ridged  to  such  an  extent  that  elevated  aqueducts  have  been  resorted  to  in 
conducting  water  over  it  for  purposes  of  irrigation.     Figure  42  exhibits  two 


Fig.  42.— Profiles  (1,000  feet  apart)  of  the  Kock  Canton  Delta,  illustrating  its  displacement  by  F.aulting 

measured  profiles  traversing  the  southern  half  of  the  delta  at  right  angles  to 
the  strike  of  the  fiiult  scarps.  If  the  reader  will  bear  in  mind  that  these 
deltas  are  normally  characterized  by  simple  profiles,  sloping  with  great  uni- 
formity from  apex  to  margin,  he  may  obtain  from  the  diagrams  some  idea 
of  the  nature  of  the  irregidarities  introduced  by  fixulting  Tlie  rods;  of  the 
mountain  is  indicated  at  the  right,  and  tlic  cliff,  a,  at  the  extreme  left  is  that 
belonging  to  the  margin  of  the  delta  The  |)ositions  of  faults  are  shown  liy 
vertical  broken  lines,  and  the  letters  h  c  d  c  mark  fault  scarps  wliich  traverse 
both  lines  of  section.     The  lines  of  section  are  alxiut  1.0(10  feet  apart,  and 


FAULTS  AT  ROCK  CANYON. 


345 


their  differences  fairly  represent  the  ordinary  variahiHty  observed  in  the 
details  of  fault  belts  when  followed  in  the  direction  of  their  strike.  A  little 
farther  north  thnn  the  position  of  the  upper  profile  the  faults  h  and  c 
approach  each  other,  and  the  fallen  block  between  them  wedges  out. 
Where  they  join,  the  trough  gives  })lace  to  a  ridge  about  five  feet  high,  and 
this  ridge,  after  running  a  short  distance  on  the  plain  of  the  delta,  reaches 
the  edo-e  overlooking-  the  stream  and  follows  down  the  stream  cliff  to  the 
flood  plain.  A  portion  of  the  fault  scarp  d  likewise  descends  the  stream  cliff, 
but  all  the  other  scarps  of  the  terrace  end  at  its  northern  margin.  It  thus 
appears  that  the  greater  part  of  the  displacement  took  place  before  the  creek 
performed  its  last  work  of  lateral  corrasion  on  the  south  side  of  its  channel, 
but  that  two  of  the  movements  are  of  later  date  The  ])henomena  are  of 
special  interest  because  they  exhibit  the  hades  of  faults,  features  very  diffi- 
cult of  observation  where  the  faulted  material  is  alluvium.  The  hade  is 
nearly  vertical,  but  inclines  slightly  toward  the  valley.  These  features  are 
shown  in  Figure  43,  in  which  the  stream  cliff  is  represented  as  seen  from 


Fig.  43. — South  half  of  Rock  Canyon  Delta,  showing  Fault  Scarps. 

the  north,  the  artist  standing  on  the  northern  half  of  the  divided  delta  and 
looking  across  the  valley  of  the  stream.  The  creek  itself  is  hidden  liy  a 
stream  teiTace  which  occupies  the  foreground  of  the  sketch,  and  it  will  be 
observed  that  this  terrace  is  likewise  traversed  by  two  small  faiilt  scarps, 
facing  each  other.     Their  height  is  only  from  two  to  four  feet,  and  by 


346  LAKE  BONNEVILLE. 

contrast  with  tlie  greater  scaqis  on  tlie  dc^lta  teiTace  beyond,  tliey  serve  to 
show  how  small  a  portion  of  the  entire  disturbance  has  occurred  since  the 
principal  excavation  of  the  stream  channel. 

The  next  observation  was  made  at  the  American  Fork,  ^hicli  debouches 
from  the  moiintain  twelve  miles  farther  north.  There,  too,  a  delta  of  the 
Bonneville  shore-line  is  centrally  divided  by  stream  erosion.  Both  halves  of 
the  delta  are  traversed  close  to  the  mountain  base  by  a  fault  scarp  GO  or  70 
feet  high.  The  same  displacement  traverses  the  flood  })lain  of  the  stream, 
but  its  throw  there  is  only  15  feet,  showing  that  the  entire  displacement  of 
the  delta  was  not  accomplished  in  a  single  movement.  The  last  disturbance 
of  the  flood  plain  was  so  recent  that  a  rapid  still  marks  the  acclivity  it  pro- 
duced in  the  bowlder-paved  stream  channel. 

A  few  miles  northward  the  scarp  was  seen  to  traverse  the  Pleistocene 
alluvial  plain  at  the  mouth  of  Dry  Canyon,  and  also  the  moraine  with  which 
that  plain  is  associated.  This  locality  is  close  to  the  jwint  where  the  Tra- 
verse Range  joins  the  Wasatch,  but  the  fault  was  not  traced  far  enough  to 
ascertain  its  relation  to  the  junction.  There  can  be  no  question,  however, 
that  the  great  fault  passes  between  the  two  ranges,  and  it  is  jirobable  that  a 
recent  movement  has  characterized  it  here  as  elsewhere.  On  tlie  north  side 
of  the  Traverse  Range  the  fault  scarp  at  the  base  of  the  Wasatch  was  traced 
quite  to  the  junction  and  seen  to  rise  in  the  groin  between  the  two  masses. 

In  the  next  ten  miles  northward,  there  issue  from  the  Wasatch  three 
creeks,  known  as  Dry  Cottonwood,  Little  Cottonwood,  and  Big  Cotton- 
wood,' and  the  fault  was  continuously  traced  by  its  scarps  past  all  these. 
In  the  vicinity  of  the  streams  and  in  the  intervals  between  them  the  surface 
disturbances  are  complicated,  and  for  a  distance  of  about  5  miles  there  run 
op])osing  scarps,  between  which  a  block  has  been  depressed.  At  the  mouths 
of  Dry  Cottonwood  and  Little  Cottonwood  canyons  the  scarps  cross  a  sys- 
tem of  moraines,  described  in  Chapter  VI  and  represented  in  PI.  XLII,  and 
materially  modify  their  forms.  The  lateral  and  terminal  moraines  of  Drv 
Cottonwood  Canyon  originally  constituted  a  loop,  the  extremitA'  of  \\  liicli 
was  notched  by  the  creek.  The  depressed  block,  traversing  the  latcial 
moraines,  has  carried  doAvn  segments  of  them,  leaving  the  distal  portions  as 

'  In  PI.  XLII  tlio  name  "  Big  Cottonwood  "  is  erroneously  attached  to  Dry  Cottonwood  Creek. 


U  S. GEOLOGICAL    SUF.VEY 


IlAKE   BONNEVILLE,    PL.XUI 


MAP  OF  THE 

M  ()  r  T  II   s 

111-- 

LITTLK  .\N7)  DRY   COTTONWOOD    CANONS, 

At  Ihc  Wi-slcni  IJasc  ul'  llir  Wasalc  li    Movuilains,  I'Lili ,  VV 

shewing 

GLACIAL    MOIJAINKS    ANI1  FALL  T  S 

Topography  I'v  lUIberr  Tlionipsoii 
Cc'oIo^Sv  bv  OK  Gilbert 


Ltitcrnl     tiitil     Ttrnnn*tl  v 


ICjOO 
SCALE     't^  ^  ^  r 


2000  3000 

--^— :     FEET 


S{)-/fe^     Ion.  U'li  r 


.IuUu«  Ilicn  ft  I'o.Iith 


DriiwTi  by  li  TliouipS' 


w.' 


FAULTS  AT  THE  COTTONWOODS. 


347 


Fin.  44.—  Profile  of  the  South  Moraine  at  the  mouth  of  Little  Cot- 
tonwood Canyon,  ahowing  the  effect  of  Faulting. 


a  pair  of  outlying  hills.     'I'lic  .southci-u  lateral  moraiiiu  of  Ivittle  Cottonwood, 
an  acute  and  originally  sj-minetric  ridge,  has  assumed  the  profile  repre- 
sented in  Fig.  4*4.     Tlie  iiortlieni  lateral,  being  broad  and  Hat,  exhibits  a 
conspicuous    trench    where 
crossed    by    the    depressed 
block  (see  PI.  XLIII).    The 
walls    of    this    trench    are 
among    the  freshest  of  the 
fault   scarps,  being  bare  of 

vegetation  along  their  upper  courses,  and  in  places  too  steep  to  be  climljed. 
(_)n  the  side  nearest  the  mountain  their  height  is  from  40  to  60  feet.  Here 
again  it  is  evident  tliat  the  total  displacement  was  accomjjlished  by  a 
series  of  efforts,  for  lietween  the  two  moraines  the  phenomena  of  the 
depressed  block  appear  in  the  alluvial  jilain  of  Little  Cottonwood  Creek, 
and  the  greatest  scarp  in  the  plain  has  a  height  of  only  20  feet.  At  Big 
Cottonwood  Creek  the  total  displacement  is  about  40  feet,  and  at  a  ])oint 
between  the  two  streams  a  single  scarp  was  observed  with  a  throw  of  100 
feet.     Fig.  45,  gi"v"ing  a  profile  of  fault  scarps  near  Big  Cottonwood  Creek, 

is  not  based  on  measurement,  but 
reprodtices  a  rough  field  sketch. 
It  is  probable  that  faults  traverse 
the  ancient  deltas  of  Little  C'otton- 
wood  Creek  at  a  distance  of  some 
miles  from  the  moinitain  base,  but  this  fact  was  not  fully  established. 

From  a  point  about  one  mile  noi-tli  of  Big  Cottonwood  Creek  to  Salt 
Lake  Cit}^,  a  distance  often  miles,  the  fault  records  are  obscure,  and  it  is  prob- 
able that  there  have  been  no  very  recent  movements.  No  scarps  at  all  were 
seen  close  to  the  rock  of  the  mountain.  It  was  thought,  that  an  old  one 
could  be  traced  a  short  distance  along  the  middle  of  the  alluvial  slope  below 
Fort  Douglas,  and  there  is  a  more  decided  indication  at  the  foot  of  the  same 
slope  in  the  eastern  suburbs  of  Salt  Lake  City.  Both  of  these  are  ancient 
as  compared  with  the  scarps  previously  described,  and  they  may  even  have 
been  washed  by  the  later  waters  of  Lake  Bonneville. 


Fig.  45.— Profile  of  Fault  Scarp.s  near  Big  Cottonwood 
Canyon. 


348  LAKE  BONNEVILLE. 

Salt  Lake  City  is  built  just  soutli  of  a  spur  which  jji-qjects  four  or  five 
miles  westward  from  the  front  of  the  Wasatch.  Tliis  spur  rcpi-esents  an 
orogenic  block  distinct  from  that  of  the  main  range.  It  is  separated  from 
the  mountain  mass  by  a  fault  plane  along  which  the  Wasatch  block  has, 
relatively  speaking,  risen,  and  it  is  separated  from  the  valley  on  the  remain- 
ing three  sides  by  a  curved  fault  plane  along  which  the  block  underlying 
the  valley  has,  relatively  speaking,  fallen.  The  first  of  these  faults  has  been 
determined  from  the  rock  .structure,  as  I  am  informed  by  Mr.  J.  E.  Clayton 
of  Salt  Lake  City.  It  is  also  indicated  at  its  northern  end  by  a  fault  scarp, 
which  can  be  traced  for  a  short  distance  up  the  groin.  The  fault  on  the 
side  of  the  valley  is  exhibited  at  the  west  and  northwest  by  a  series  of 
scarps,  which  begin  in  the  northern  suburbs  of  Salt  Lake  City  near  the 
Warm  Springs.  At  this  point  the  flat  alluvial  plain  of  the  Jordan  reaches 
the  steep  rock  face  of  the  spur,  the  line  of  separation  being  marked  by  an 
abrupt  change  of  slope.  A  little  north  of  the  springs  there  can  be  seen 
clinging  to  the  rock  at  a  height  of  40  feet  a  line  of  conglomerate  fragments, 
formed  within  the  plain  by  the  cementation  of  debris  to  the  limestone,  and 
brought  by  faulting  into  the  present  position.  The  surface  of  the  plain 
below  is  thrown  by  the  same  faulting  into  irregular  waves,  and  at  one  point 
it  is  distinctly  terraced.  On  one  of  the  faulted  benches  an  ore-reducing 
establishment  has  been  built,  utilizing  a  lower  bench  as  a  dmTiping  ground 
for  its  slag.  Between  this  point  and  the  liot  spring  an  alluvial  cone,  Ijuilt 
against  the  face  of  the  spur,  is  traversed  by  a  typical  scarp,  which  was 
sketched  by  Mr.  Holmes.  Tlie  sketch  is  reproduced  in  PI.  XLIV,  where 
may  be  seen  not  only  the  scarp  but  its  relation  to  other  elements  of  the  local 
geologic  history.  The  face  of  the  spur  consists  of  a  paleozoic  limestone, 
inclined  at  various  high  angles.  The  horizontal  terraces  it  liears  are  shore 
marks  of  the  ancient  lake.  It  is  evident  that  the  principal  features  of  its 
relief  had  been  carved  before  the  production  of  these  terraces,  so  that  the 
main  displacement — that  to  which  the  spur  owes  its  origin — nuist  have 
occurred  long  before  the  Bonneville  epoch.  The  alhn  ial  cone  may  or  may 
not  have  been  constructed  before  the  epoch  of  the  lake,  but  by  the  absence 
of  shore-lines  and  lake  beds  from  its  surface  we  are  assured  tliat  its  outer 
layers  at  least  are  of  post-Bonueville  deposition.     The  disi)lacements  pro- 


U.  S.   GEOLOGICAL  SURVEY 


LA^:e   eOflNEVILLE        PL,    XLIV 


V 


.> 


'^" 


^0Mi^l^ 


'%■ 


'"^•-\\- 


R^ 


-t0B-'N}'£!KH.l-  S'c'^ts-s 


FAULT  SCARP  CROSSING  ALLUVIAL  CONE,   NEAR  SALT  LAKE  CITY. 
Drawn  by  W.  H.  Holmes. 


FAULTS  NEAR  SALT  LAKE  CITY.  349 

ducing  the  fault  scarps  are  therefore  subsequent  not  only  to  the  lake  but  to 
a  certain  amount  of  post-lacustral  alluviation. 

The  portion  of  the  alluvial  cone  that  lies  above  the  fault  scarp  is  chan- 
neled by  the  stream,  and  a  study  of  the  system  of  terraces  bordering  this 
channel  shows  that  the  total  displacement  of  30  feet  was  produced  by  at 
least  tln-ee  independent  movements,  the  measures  of  the  parts  being  15  feet, 
5  feet,  and  10  feet. 

At  this  point  and  elsewhere  in  the  vicinity  the  scarp  is  utilized  by 
burners  of  lime,  who  construct  their  kilns  against  its  face  and  use  the 
terraces  above  and  below  for  the  two  approaches  needed  in  the  man- 
agement of  the  kilns.  The  proprietor  of  the  kiln  represented  in  the  plate 
enjoys  the  further  convenience  of  quarrying  his  limestone  from  the  adja- 
cent cliff. 

The  hot  spring  at  the  apex  of  the  spvir  is  on  the  line  of  the  fai;lt,  and 
a  scarp  can  be  traced  from  it  in  either  direction.  The  powder  houses  stand- 
ing a  little  farther  northward  are  partly  above  and  partly  below  the  fault 
scarp.  Many  of  the  fault  features  in  this  vicinity,  including  those  figured 
in  PI.  XLIV,  may  be  seen  from  the  car  windows  of  trains  passing  between 
Salt  Lake  City  and  Ogdeu. 

From  the  point  where  the  spur  joins  the  main  ridge  northward  to  the 
ancient  delta  of  the  Weber,  a  continuous  scarp  follows  the  mountain  base, 
its  throw  ranging  from  25  to  75  feet.  Opposite  the  village  of  Farmington 
its  course  is  less  direct  than  the  trend  of  the  mountain  front,  causing  it  to 
ascend  and  descend  the  narrow  alluvial  foot  slope  in  the  manner  represented 
in  Fig.  46.  The  broad  Weber  delta,  which  belongs  chiefly  to  the  Provo 
epoch,  is  crossed  from  side  to  side  by  the  scarp,  the  general  throw  being 
from  40  to  50  feet.  A  recent  alluvial  cone  resting  upon  the  southern  half 
of  the  delta  has  suffered  a  displacement  only  one-third  as  great  as  the  adja- 
cent delta.  On  the  northern  half  of  the  delta  the  scarps  constitute  a  sys- 
tem similar  to  that  in  the  delta  of  Rock  Canyon,  and  there  are  transverse 
branches  running  half  a  mile  westward  into  the  plain.  At  one  point  the 
falling  of  a  block  has  produced  on  the  surface  a  closed  basin,  which  with  a 
little  artificial  improvement  has  been  made  to  serve  for  the  storage  of  water 
for  irrigation. 


350 


LAKli  BONNEVILLE. 


Thence  to  North  Ogden  Canyon  scai7)s  were  seen  at  numerous  points 
usually  in  (>'rou])s  of  two  oi-  more.     Fig.  47  gives  iiii   iiunicMsunMl  prnliU 


Fig.  40.— Sh.'u- luir,-,  .uj.l  I'.uili  Sc.up  .a  iiulns,  ,,i  ii.r  W',.,.,., 


(■ill   F.iriiiiii^tuii,   i' 


Fig.  47.— Profile  of  Fault  Scarps  near  Ogden  Canyon,  Utah. 


across  the  displacement  near  Ogden  Canyon,  and  contains  an  extreme  illus- 
tration of  the  reversed  slope  frequently  given  to  blocks  of  alluvium  between 

parallel  faults.  A  few  miles 
farther  north  a  small  closed 
basin  has  been  foriiu'il  in  this 
manner.  In  the  same  vicinity 
one  of  the  fault  scarps  crosses 
the  line  of  the  Bonneville  shore  terrace,  dis})lacing  it  about  20  feet. 

At  North  Ogden  Canyon  the  axis  of  the  range  turns  westward  for  a  few 
miles,  and  then  resumes  its  northerly  course.  At  the  salient  angle  a  low- 
spur  is  apijended,  similar  to  that  at  Salt  Lake  City,  ]:)ut  of  smaller  dimen- 
sions. The  scar])  runs  bcliiiid  the  spur,  and  none  was  seen  alx.ut  its  tare; 
but  it  can  not  In-  doubted  that  its  boundai-y  on  the  valley  side  also  is  deter- 
mined liv  a  fauh.      .V  hot  spring  rises  near  its  western  l»ase.      'riieiice  north- 


FAULTS  IN  CACHE  VALLEY.  351 

ward  to  the  town  of  Willard  the  fault  scarp  follows  the  mountain  base  with 
an  average  throw  of  20  feet,  and  it  gradually  diminishes  and  disappears 
before  reaching  the  next  settlement,  Brigham  City.  Beyond  Brighani  City 
a  single  locality  only,  near  the  settlement  of  Honeyville,  gave  evidence  of 
recent  movement  on  the  plane  of  the  great  Wasatch  fault. 

The  total  distance  from  Nephi  to  Honeyville  is  125  miles,  and  it  is 
probable  that  more  than  100  miles  of  that  distance  is  characterized  by  post- 
Bonneville  ftiult  scarps.     The  average  displacement  is  30  or  40  feet. 

North  of  Honeyville  the  crest  line  of  the  Wasatch  falls  so  low  that  it 
was  overflowed  by  the  Bonneville  waters.  The  axis  rises  beyond  into  a 
range  of  importance,  Ijut  the  name  Wasatch  is  not  there  applied.  If  the 
western  margin  of  this  range  is  determined  by  a  continuation  of  the  Wasatch 
fault,  no  record  of  the  fai-t  was  observed  in  recent  scarps.  A  few  scarps  were 
seen  on  the  opposite  (eastern)  side  of  the  range,  especially  in  the  vicinity 
of  Clarkston.  Twenty  miles  farther  north,  and  approximately  in  the  same 
structural  trend,  there  itre  fault  scarps  at  the  western  margin  of  Marsh  Val- 
ley, but  these  are  outside  the  Bonneville  Basin. 

The  fault  mentioned  at  Clarkston  follows  the  western  margin  of  Cache 
Valley.  The  eastern  wall  of  the  valley  is  an  important  mountain  range, 
whose  bold  western  front  has  the  topographic  configuration  of  a  worn  fault 
cliff.  At  its  base  there  are  obscure  indications  of  late  movements,  either 
during  or  just  after  the  lake  epoch,  and  at  one  point,  near  Logan,  a  post- 
lacustrine  fault  scarp  crosses  a  delta  of  Provo  date.  The  displacement  is 
about  six  feet.  At  the  north  end  of  the  valley  a "  weathered  scarp  was 
observed  near  the  base  of  the  alluvial  cone  of  Marsh  Creek,  close  to  the 
outlet  channel  of  Lake  Bonneville.  The  direction  of  its  throw  indicates 
that  it  belongs  to  the  eastern  side  of  the  valley,  but  it  is  several  miles  from 
the  mountain  front  proper. 

The  range  bordering  Cache  Valley  on  the  east  extends  southward 
parallel  to  the  Wasatch,  and  exhibits  in  Morgan  Valley,  at  its  intersection 
by  the  Weber  River,  an  old  fault  scarp,  judged  from  its  imperfect  preserva- 
tion to  be  pre-Bonneville. 

Passing  west  of  the  Wasatch  meridian,  we  have  at  the  north  a  single 
instance  of  recent  faulting.     The  small  range  lying  east  of  the  town  of  Snows- 


352  LAKE  BONNEVILLE. 

ville  is  marked  at  base  by  a  low  scarp, — a  scarp  more  defaced  by  erosion 
than  are  the  Bonneville  terraces  lower  down  on  the  same  slope.  In  tlie 
same  meridian  and  far  to  the  south  are  the  fiiults  described  in  the  last  chap- 
ter as  associated  with  the  Ice  Spring  craters.  They  are  probably  referable 
to  the  volcanic  phenomena  rather  than  to  those  of  mountain  uplift;  and  the 
same  remark  applies  to  a  scarp  observed  by  Mr.  Russell  20  miles  farther 
south. 

Midway  between  these  are  two  fault  lines,  associated  with  the  Oquirrh 
and  Aqui  ranges.  These  ranges  are  parallel  to  each  other  and  to  the  Wa- 
satch, and  agree  with  that  range  in  having  their  main  lines  of  displacement 
on  the  western  side.  The  scarp  at  the  western  base  of  the  Oquin-h  runs 
southward  from  Lake  Point  a  distance  of  four  miles,  exhibiting  a  throw  of 
25  feet.  Its  position  is  at  the  base  of  the  pteep  mountain  face,  and  the  Bonne- 
ville and  Provo  terraces  are  carved  in  the  x'ock  above.  It  was  next  seen 
a  few  miles  farther  south,  where  it  follows  the  contour  of  an  embajnuent  of 
the  mountain  side.  It  is  there  partly  above  and  partly  below  the  level  of 
the  Bonneville  shore-line.  Near  the  town  of  Tooele  it  appears  to  strike 
across  a  transverse  spur,  reappearing  southward  at  the  mouth  of  what  is 
called  Dry  Canyon,  and  continuing  thence  to  East  Canyon  and  the  canyon 
which  contains  the  mining  hamlet  of  Lewiston.  At  the  mouth  of  East  Can- 
yon it  intersects  alluvial  terraces  in  such  way  as  to  show  two  separate 
movements  with  an  aggregate  tlu'ow  of  50  feet.  Although  the  course  of 
the  scarp  was  not  traced,  it  is  believed  that  it  could  be  followed  continu- 
ously for  a  distance  of  25  miles.  The  southern  portion  nms  above  the  hor- 
izon of  the  lake  shores,  and  is  therefore  not  directly  comparable  Avith  them, . 
but  it  is  considered  probable  that  post-Bonneville  movements  have  occurred 
at  all  points  of  observation.  The  scarp  on  the  Aqui  Range  is  low,  and 
there  is  small  basis  for  judgment  as  to  its  date.  It  was  best  seen  in  the 
vicinity  of  Knowlton's  ranch. 

Following  westward  along  the  system  of  ranges  which  separate  the  main 
body  of  Lake  Bonneville  from  the  Sevier  body  observation  is  purely  nega- 
tive until  the  House  Range  is  reached.  It  is  proper  to  say,  however,  that 
so  much  attention  was  given  to  mountain  foot  slopes  in  connection  witli  the 
study  of  shore-lines  that  the  absence  of  notable  fault  scarps  may  be  asserted 


U  S.GBOLOGICAL    SURVEY 


LAKE  BONNEVILLE      PL.  XDV 


i 


113° 


112° 


111 


111° 


Julius  Bicn  i  t'o,  Ulh 


Drmm  bv  G.TI...uipi« 


FAULTS  OF  WESTERN  UTAB.  353 

of  the  southern  portion  of  the  Cedar  Rang-e,  of  the  eastern  face  of  the  Simp- 
son and  the  western  face  of  the  McDowell,  of  Granite  Rock,  and  of  the 
northern  portion  of  the  Dugway  Range. 

The  Plouse  Range  was  long  ago  recognized  as  a  faulted  monocline  in 
which  the  direction  of  displacement  is  reversed  midway.  The  northern 
third  of  the  range  exhibits  a  westerly  dip,  and  is  faulted  along  the  eastern 
base ;  the  southern  part  has  an  easterly  dip  and  is  faulted  on  the  western 
base.^  This  determination  was  subsequently  confirmed  .by  the  discovery 
of  a  \vell  defined  fault  scarp  in  the  vicinity  of  Fish  Si)ring,  and  an  obscure 
and  probably  very  ancient  scarp  at  the  western  base  of  the  southern  division. 

The  next  mountain  body  to  the  west  is  the  Confusion  Range,  an 
assemblage  of  small  ridges,  and  associated  with  these  a,  single  scarp  was 
found.  This  lies  near  Knoll  Springs,  on  the  east  side  of  Snake  Valley.  It 
is  low  and  worn,  and  follows  the  rock  base  closely. 

The  Deep  Creek  Range,  which  forms  part  of  the  western  boundary  of 
the  Bonneville  Basin,  is  faulted  on  both  sides.  In  the  vicinity  of  the  old 
overland  road  crossing  the  ridge  from  Willow  Spring  to  Deep  Creek  settle- 
ment, to  which  vicinity  observation  was  restricted,  the  range  is  flanked  on 
the  east  by  a  broad  and  high  alluvial  slope.  No  fault  scarp  was  seen,  but 
near  the  lower  margin  of  the  slope  a  partial  section  of  the  lake  sediments 
shows  that  they  were  disturbed  during  the  period  of  their  deposition.  The 
Yellow  Clay  at  one  place  suifered  uplift  and  erosion  before  the  deposition  of 
the  White  Marl,  so  that  there  is  unconformity  of  dips,  and  at  another  point 
the  Yellow  Clay  and  White  Marl  together  are  so  greatly  disturbed  that  their 
inclination  is  toward  the  mountain.  The  superficial  topograjihy  that  must 
have  been  created  by  these  disturbances  was  obliterated  by  wave  work, 
and  at  the  locality  of  the  section  the  upper  edge  of  the  inclined  block  was 
planed  away  in  the  formation  of  a  terrace  of  the  Provo  shore. 

On  the  west  side  of  the  range  an  ancient  and  nearly  obliterated  scarp 
crosses  the  alluvial  slope  near  its  upper  edge.  On  the  opposite  side  of  Deep 
Creek  Valley  a  better  preserved  fault  scarp  follows  the  eastern  base  of  the 
Gosiute  range.  It  lies  far  above  the  Bonneville  shore-line,  and  was  not 
critically  examined. 

'  Surveys  West  of  the  100th  Meridian,  vol.  3,  pp.  27-28. 
MON  I 23 


354  LAKE  BONNEVILLE. 

GENERAL  FEATURES  OF  FAULT  SCARPS. 

Except  in  the  yolcanic  district  of  the  Sevier  Desert,  the  fault  scarps 
follow  the  bases  of  mountain  ranges  or  run  })arallel  to  them.  Where  there 
is  but  a  single  scarp,  it  invariably  fiices  toward  the  valley  and  away  from 
the  mountain.  Where  there  are  several  scarps,  frequently  one  or  more  face 
toward  the  mf)untain,  but  the  one  nearest  the  mountain  always  faces  toward 
the  valley,  and  the  net  displacement  is  always  of  such  nature  as  to  inci-ease 
the  height  of  the  mountain  with  reference  to  the  valley.  The  mountains 
are  rising  ar  the  valleys  sinking. 

The  scarps  are  rarely  found  at  the  contact  of  the  rock  of  the  mountain 
with  the  alluvium  of  the  valley;  they  usually  occur  in  the  alluvium  several 
scores  or  lumdreds  of  feet  from  the  contact.  The  segments  of  alluvial  plain 
included  between  parallel  scarps  rarely  retain  their  original  slope.  In  a  few 
instances,  and  for  short  distances,  their  rate  of  descent  toward  the  valley  is 
increased  by  the  disturbance,  but  as  a  general  rule  the  slope  valleyward  is 
diminished,  or  even  i-eversed.  The  tendency  of  the  dissevered  blocks  to 
incline  away  from  the  side  of  the  downthrow  is  almost  as  pronounced  as  in 
the  case  of  land  slides.  The  assumption  that  the  attitudes  of  these  alluvial 
surfaces  are  representative  of  the  attitudes  of  large  down-reaching  masses 
continuous  with  them  seems  untenable,  because  such  masses  would  mutually 
interfere. 

The  hade  of  a  fault  is  usually  difficult  of  determination  unless  expo.sed 
by  mining  operations,  and  the  difficulty  is  peculiarly  great  where  the  walls 
are  of  incoherent  detritus.  The  freshest  of  tlie  fault  scarps  have  some  talus, 
and  prove  only  that  the  hade  does  not  depari  widely  from  verticality.  The 
best  observation  w^as  made  in  the  Rock  ('nnvon  delta,  where,  as  already 
described,  several  scarps  descend  a  stream  cliti'  standing  at  tlu-  angle  of 
stabilitv.     They  show  a  hade  toward  the  valley  of  less  tlian  li\  e  degrees. 

That  this  approximate  verticality  is  more  than  a  superficial  feature  of 
the  great  Wasatch  fiinlt,  is  seri(iusl\-  ([uestioiied,  for  several  reasons.  In 
the  first  place  the  faults  witliin  the  Hasin  Ranges,  so  far  as  niv  observation 
shows,  hade  at  consideralih-  angles,  and  it  is  liiglily  probable  that  this  fault 
belongs  to  the  same  system.  Second,  tlie  secular  motion  of  the  mountain 
being  upward  with  reference  to  the  valley,  it  is  prol)able  that  the  roek  face 


THEORY  OF  FAULT  SCARPS. 


355 


at  the  contact  Avith  alluvium  lias  lieeu  little  Avasted  by  erosion,  and  is  essen- 
tially the  protruded  foot-wall  of  the  fault,  and  if  so,  the  visible  fault  iu 
alluvium  is  not  in  the  plane  of  the  great  fault,  but  is  a  branch  with  less 
hade.  Finally,  the  last  hypothesis  affords  an  easy  explanation  of  the  super- 
ficial details  of  the  faulting,  as  will  appear  by  the  following  explanation. 

Fig.  48  is  constituted  of  four  diagrams  illustrating  the  supposed  method 
of  faulting.  In  the  first  diagram  the  line  ,r  ij  represents  in  section  the 
Wasatch  fault,  with  an  assumed  hade  of  30°.     To  the  right  of  this  line  is 


Fig.  48. — Diagram  to  illuatrate  Theory  of  Grouped  Fault  Scarps  in  Alluvium, 

the  firm  rock  of  the  mountain,  its  surface  being  somewhat  reduced  by  ei'O- 
sion  above  the  point  a,  where  the  alluvial  slope  of  the  valley  side  adjoins  it. 
To  the  left  of  the  line  x  y  the  material  represented  is  detrital  and  incoherent, 
being  chiefly  alluvial.  The  alluvial  sui'face  previous  to  the  last  faulting  is 
represented  by  a  c.  The  direction  of  motion  in  faulting  is  parallel  to  the 
plane  x  y,  and  the  plane  of  motion  is  assumed  to  coincide  Avith  that  plane 
up  to  the  point  c,  and  then  curA-e  to  &,  so  that  a  triangular  pi-ism  of  allu- 
vium, ft  h  e,  remains  attached  to  the  rock,  constituting  the  foot-Avall  of  the 
fault.  This  movement  opens  a  fissure,  h  e  (J.  The  material  traversed  by  it 
being  incoherent  or  feebly  coherent,  the  fissure  cannot  remain  open,  but  is 
immediately  filled  by  the  settling  of  one  or  both  of  the  Avails.  The  remain- 
ing three  diagrams  indicate  hypothetical  methods  of  closing  the  fissure.  In 
the  second  diagram  it  is  supposed  that  the  hanging  wall  yields  Avithout  defi- 
nite fracture,  Imt  l»y  differential  moA'einent  distributed  throughout  tlu*  mass, 
so  that  the  triangular  prism  included  between  the  points  //  d  e  is  made  to 
assume  the  form  and  position  // ./'  e.  There  then  remains  a  fai^lt  scarp,  h  f, 
giving  an  exaggerated  measure  of  the  actual  throAv  of  the  fault  h  d,  and 


35(j  LAKE  BONNEVILLE. 

accompanied  at  its  base  hy  a  reversed  inclina,tion  of  the  surface///  In 
the  third  diagram  it  is  assumed  that  the  hanging  wall  is  divided  by  a  fract- 
ure, /;  e,  and  that  the  prism  h  d  c  settles  and  spreads  so  as  to  occupy  the 
space  i  k  e.  There  result  two  fault  scarps,  h  k  and  Ji  '/,  facing  in  opposite 
directions  and  api)roximately  representing  l)y  their  difference  the  true  throw 
h  (J.  The  fourth  diagram  supi)oses  that  the  triangular  prism  h  I  o  in  cleaved 
from  the  up})er  part  of  the  foot-wall  and  slides  down  so  as  to  take  the  posi- 
tion m  n  e.  This  gives  two  fault  scarps,  /  n  and  m  d,  whose  sum  would 
ordinarily  att'ord  an  overestimate  of  the  actual  movement  of  the  great  fault 
plane.  If  now  we  consider  that  there  have  been  repeated  movements  along 
the  same  general  plane  of  faulting,  and  that  these  repetitive  displacements 
have  often  divided  the  alluvium  in  different  places,  it  becomes  evident  that 
these  hypothetic  elementary  profiles  can  be  so  combined  as  to  jjroduce  all 
the  complicated  profiles  actually  observed. 

While,  as  just  mentioned,  a  number  of  successive  movements  may  occa- 
sion the  same  number  of  separate  scarps,  they  may  also  coincide  in  locus 
and  produce  but  one,  and  it  is  probable  that  coincidence  is  the  rule.  In 
general,  each  scarp  represents  a  series  of  distinct  movements. 

Indeed,  so  far  as  the  phenomena  of  the  Bonneville  Basin  instruct  us, 
the  process  of  faulting  might  be  conceived  as  one  of  continuous  sl(i\\-  motion, 
and  it  is  only  through  the  phenomena  of  earth(piakes  in  other  districts  that 
we  become  acquainted  with  the  rhythmic  and  paroxysmal  nature  of  dis- 
placement on  surfaces  of  fracture.  The  features  of  the  fault  scarps  accord 
fully  with  the  general  theory  that  the  growth  of  mountains  is  a  gradual 
])rocess,  secular  in  duration,  though  (•atastrophic  in  detail. 

The  freshness  of  some  of  the  scarps  points  to  an  anti(puty  measured  in 
>ears  rather  than  centuries.  A  large  number  have  l)een  ])roduced  since  the 
final  retirement  of  the  Bonneville  waters.  A  few  were  synchronous  wilh 
the  I'rovo  shore-line.  One  movement  l)elongs  to  inter-lSoiniexille  time.  ( )t 
earlier  dates,  nothing  can  be  said  with  precision.  Inside  the  lake  area,  it 
is  to  be  sujjposed  that  scarps  older  than  the  Bonneville  shore-line  were  olilit- 
erated  l)^-  littoral  sculpture  and  lacustrine  sedimeiitatiiin.  ( tutside  the  Bon- 
neville shore-line  the  only  discovered  index  of  anti(piity  is  the  state  of  pres- 
ervation, a  criterion  affording  no  precision.      Discrimination  is  further  em- 


OLD  FAULTS  AND  YOUNG.  357 

barrassed  by  the  recunviict'  of  ilisplncemeiit  nloiii;-  tlic  same  lines,  so  tlint 
tlie  qualified  indications  of  date  in  the  preceding  pages  apph'  as  a  lailc  onl\- 
to  the  latest  of  the  local  movements. 

LOCAL  DISPLACEMENTS   VERSUS  LOCAL  LOADING    AND  UNLOADING. 

The  phenomena  of  earthquakes  indicate  that  the  orogenic  forces,  what- 
ever they  may  be,  slo\vl\-  generate  and  accumulate  strains  in  the  crust, 
until  finally  the  cohesion  or  static  friction  is  overcome,  and  a  sudden  Nield- 
ing  results  in  a  fault  and  an  earthquake.  In  such  a  district  as  the  liomie- 
ville  Basin,  where  the  planes  of  faulting,  su})erficially  at  least,  are  approxi- 
mately vertical,  it  seems  probable  that  the  determination  of  rupture  may  be 
hastened  or  retarded  by  anything  affecting  the  weight  of  the  orogenic  block 
on  either  side  of  the  plane  of  movement.  It  is  coimnonly  held  by  students 
of  physical  geology  that  the  degradation  of  the  uplifted  block  and  the  accu- 
mulation of  sediment  on  the  downthrown  block  constitute  an  unloading  and 
a  loading,  which  consijire  with  and  aid  the  forces  primarily  concerned  in  the 
displacement,  and  it  is  maintained  by  some  that  when  once  the  displace- 
ment along  a  great  fault  line  has  been  initiated,  the  process  of  loading  and 
unloading  is  competent  to  continue  the  depression  of  the  lower  block  and 
the  upheaval  of  the  higher  without  further  aid  from  the  forces  that  initiated 
the  disturbance.  Now  the  filling  of  the  Bonneville  Basin  with  water  added 
a  very  considerable  weight  to  the  vallej's,  and  therefore  to  the  down-thrown 
blocks,  and  made  no  corresponding  addition  to  the  uplifted  blocks  repre- 
sented in  the  mountain  ranges.  The  contemporaneous  glaciers  were  indeed 
sustained  by  uplifted  blocks,  but  these  were  restricted  to  a  short  section  of 
the  Wasatch,  and  in  that  section  their  weight  was  much  less  than  that  of 
the  water  in  the  adjacent  valley.^  It  is  therefore  theoretically  conceivalile 
that  during  the  presence  of  the  lake  the  pi-ocess  of  faulting  along  the.mount- 
ain  bases  was  stimulated,  and  that  after  the  evaporation  of  the  water  the 
process  was  corre.spondingly  retarded.  That  the  load  of  water  was  quanti- 
tatively sufficient  is  readily  shown.  If  the  transfer  of  rocky  matter  from 
the  mountain  block  to  the  valle)'  block  is  the  cause  ordinarily  operative  in 

'The  ,irea  of  ice  on  tbo  Wasatch  Range  inay  be  compared  with  the  contemporaneous  area  of 
water  in  Lake  Bonneville  by  reference  to  PI.  XLIX.  The  areas  of  ice  there  represented  on  the  Wasatch 
and  Uintah  Mountains  are  copied  from  Kin^^'s  map  in  Volume  I  of  the  Fortieth  Parallel  Report. 


358  LAKE  BONNEVILLE. 

generating  the  stress  which  renews  movement  along  the  fault  plane  between 
the  blocks,  then  the  dejjth  of  rock  necessary  to  be  removed  from  one  block 
and  added  to  the  other  in  order  to  overcome  the  adhesion  on  the  fault  i)lane 
is  measured  by  one-half  the  resulting  movement.  For  the  Wasatch  range 
this  measiu-e  is  less  than  five  feet.  The  load  of  water  held  by  the  valley 
blocks  was  e(|ui\alent  in  the  vicinity  of  Great  Salt  Lake  to  a  layer  of  rock 
of  the  density  of  the  surrounding  mountains  and  with  a  tliickness  of  300 
feet,  and  at  the  Provo  stage  the  load  of  water  wns  equivalent  to  200  feet  of 
rock.  The  stress  due  to  the  water  was  therefore  many  times  greaU'v  than 
that  needed  to  over})ower  the  adhesion,  and  the  load  of  A\iiter  was  com- 
petent to  act,  provided  the  erogenic  blocks  possessed  the  tlieoretic  susceji- 
til)ilitv  to  lonil. 

If  tlie  orogenic  blocks  rest  on  a  ])lastic  substratmn,  or  if  thev  are  oth- 
erwise conditioned  so  as  to  obey  the  hydrostatic  law  and  yield  freely  to 
external  stresses,  then  the  valley  blocks  should  have  been  depressed  several 
hundred  feet  by  the  adilidon  (if  the  water,  should  have  partially  recovered 
from  this  depression  during  tlie  abrupt  lowering  of  the  lake  from  the  Bon- 
neville shore  to  the  Provt),  and  should  have  risen  still  further  during  the 
final  desiccation  of  the  basin,  except  in  regions  where  the  orogenic  forces 
operated  Avitli  sufficient  rapidity  to  counteract  the  tendency.  Instead  of 
this,  we  find  that  the  post-Bonneville  movement  of  the  valley  blocks, 
wdierever  it  has  occurred,  has  been  one  of  depression,  and  so  far  as  the 
})henoraena  go  we  find  no  evidence  that  the  depression  of  the  valleys  was 
more  rapid  during  the  epochs  of  tha  Bonneville  and  Provo  shores  than  it 
has  been  in  more  recent  times. 

We  are  forced  to  conclude  that  the  mountain  ranges  of  the  Bonneville 
Basin  and  the  valle}'s  between  tlicin  do  not,  with  reference  to  each  other, 
obey  tlie  law  of  flotation. 

It  follows  with  eqiud  cogency  that  the  faults  do  not  penetrate  to  a 
layer  characterized  by  fluidity  or  semi-fluidity — implying  by  these  terms 
the  ])ower  to  flow  under  small  shearing  strain — but  terminate  in  a  region  of 
rigidity — im]dving  by  that  term  the  ability  to  withstand  relatively  large 
shearing  strain.  I  conceive  them  to  ternnnate  at  the  up])er  limit  of  the 
i-egiou  of  plasticity  by  pressure — implying  by  that  phrase  that  at  and  below 


FAULTING  INDEPENDENT  OF  LAKE  HISTORY.  359 

» 

a  certain  deptli  the  rocks  of  tlie  crust,  liowevor  riyid,   iire  subject  to  such 

pressure  that  their  j'ielding  under  shearing  strains  exceeding  tlie  ehistic 
limit  is  not  by  fracture  but  l)y  flow.  I  conceive  the  orogenic  blocks  as 
confluent  with  the  subjacent  layer,  excepting  such  as  may  wedge  out  by 
the  convergence  of  fault  ])lanes. 

MOUNTAIN    GROWTH. 

The  height  of  ;)  mountain,  considei'ed  as  a  to])ographic  feature,  is  the 
altitude  of  its  crest,  not  above  sea-level,  but  above  the  surroiuiding  country. 
From  this  ])oint  of  view  it  is  pertinent  to  inquire  whether  the  mountains  of 
the  Bonneville  basin  are  now  growing.  The  C[uestion  is  more  easily  asked 
than  answered,  but  its  consideration  may  not  be  unprofitable  even  thougli 
the  residt  is  indefinite. 

In  the  case  of  mountains  whose  uplift  takes  place  along  faidt  i)lanes, 
the  amount  of  faulting  is  a  measure  of  the  uplift.  If  the  faulting  is  at  one 
margin  only  and  the  f)ther  margin  suflers  no  displacement,  then  the  general 
uplift  above  the  adjacent  valleys  is  one-half  the  uplift  at  the  fault  lines. 
The  processes  of  degradation  tend  constantly  to  pare  away  the  mountain 
top  and  thus  reduce  its  height,  and  in  the  district  under  consideration  tlie 
processes  of  valley  sedimentation  likewise  reduce  the  mountain  height  by 
building  up  the  valleys  and  thereby  raising  the  plane  of  reference.  When- 
ever and  wherever  diastrophism  is  the  more  active,  the  mountain  grows; 
when  degradation  and  sedimentation  are  moi'e  active,  the  mountain  becomes 
smaller.  The  post-Bonneville  faulting  of  the  Wasatch  Range  is  restricted, 
so  far  as  known,  to  the  western  base,  and  there  amounts  to  about  40  feet. 
Tlie  general  u])lift  of  the  range  may  therefore  be  taken  at  20  feet.  Tlie 
product  of  the  simultaneous  degradation  of  tlie  niount;iin  finds  its  way  to 
Utah  Lake  and  Great  Salt  Lake,  where  its  coarser  j)art  is  accumulated  in 
the  deltas  of  the  Provo,  the  Jordan  and  the  Weber,  while  its  finer  j^ortion 
is  spread  over  the  lake  bottoms.  P)ut  the  deltas  and  lake  beds  afford  no 
simple  measure  of  the  mountain  waste,  for  the  same  rivers  receive  also 
detritus  from  other  land  areas,  and  in  the  same  lakes  are  gathered  the  silts 
from  other  streams.  The  deposits,  moreover,  are  unex])lored,  and  if  they 
were  explored,  it  would  be  no  easy  matter  to  discriminate  the  post-Bonne- 


360  LAKE  BONNEVILLE, 

ville  deposits  from  the  Bonneville  beds  beneath  them.  The  problem  might 
be  attacked  by  a  consideivntion  of  the  annual  outwash  of  the  mountain  tor- 
rents, but  if  this  difficult  measure  were  made,  we  should  still  need  to  know 
the  antiquity  in  years  of  the  last  Bonneville  flood,  a  factor  for  the  present 
entirely  unknown. 

But  though  a  categorical  answer  is  unattainable,  a  qualified  result  is 
not  necessarily  so.  The  recent  uplift  of  the  Wasatch  Range  is  greater  than 
that  of  any  other  range  in  the  basin.  That  of  the  Oquirrh  may  be  one 
half  as  great,  but  no  other  range  is  at  all  to  be  compared  in  this  respect, 
and  many  ranges  show  no  fault  scarps  whatever.  It  may  therefore  be  said 
with  confidence  that  if  any  range  of  tlie  district  is  actually  growing  at  the 
present  time,  the  Wasatch  is  growing,  and  this  l)rings  us  to  a  theorem  of 
Powell's  which  here  finds  illustration.  Powell  pointed  out'  that  a  high 
mountain  is  subject  to  more  rapid  degradation  than  a  low  one,  and  that  the 
rate  of  degradation  is  a  geometric  function  of  the  height.  It  is  therefore 
impossible  for  a  mountain  to  become  tall  unless  it  is  uplifted  rapidly,  and 
when  uplift  ceases  or  becomes  slow,  only  a  sliort  measure  of  geologic  time 
is  necessary  to  reduce  the  height.  High  mountains  are  therefore  always 
yoinig  mountains.  They  may  be  constituted  of  very  ancient  rocks, — their 
initial  uplift  may  have  taken  place  at  a  remote  date,  but  the  great  upheaval 
which  produced  the  present  movmtain  is  geologically  recent.  The  Wasatch, 
springing  ])oldly  from  a  base  plain  8,000  feet  below  its  pinnacles,  is  a  young 
range,  and  as  its  recent  uplifting  has  been  more  rapid  than  that  of  any  of 
its  neighbors,  we  may  fairly  assume  that  present  uplift  is  in  excess  of  pres- 
ent waste,  and  that  the  mountain  is  now  growing. 

EARTHQUAKES. 

The  extreme  recency  of  tlie  last  orogenic  movements  in  the  most 
populous  portion  of  Utah,  and  the  high  ])robal)ility  of  their  recuiTence 
in  the  future,  have  a  practical  bearing  as  well  as  a  scientific,  for  it  is  now 
generally  imderstood  that  earthquakes  are  due  to  paroxysmal  yieldings  of 
the  earth's  crust,  and  it  is  e(|uall\-  well  known  that  tlie  dangers  attending 
earthquakes  can  be  greatly  diminislu-d  b\-  precautionary  measures.     It  is 

'  Geology  of  the  Eastern  Portion  of  the  Uinta  Mountains,  by  J.  W.  Powell,  Washington,  1876, 
p.  196. 


FAULT  SCARPS  AND  EARTHQUAKES.  361 

indeed  true  that  the  fault  scarps  at  the  base  of  the  Wasatch  Mountams  have 
not  been  directly  connected  with  earth  tremors,  but  the  association  of 
identical  phenomena  has  been  elsewhere  observed.  The  earthquake  of 
1872,  one  of  the  most  violent  ever  felt  in  the  United  .States,  originated  in 
Owen's  Valley,  California,  and  its  origin  was  accomjjanied  by  the  sinking 
of  strips  of  land  in  such  way  as  to  jjroduce  fault  scarps  identical  in  their 
general  features  with  those  described  in  the  preceding  pages.  The  principal 
scarp  follows  the  base  of  the  alluvial  foot  slope  of  the  Sierra  Nevada,  and 
has  a  maximum  height  of  about  20  feet.  Where  this  height  is  attained, 
there  is  a  coinpanion  fault  scai-p,  10  feet  high,  facing  in  the  opposite  direc- 
tion, so  that  the  net  displacement  is  about  10  feet.  At  other  points  the 
main  scarp  is  associated  with  others  miming  nearly  ])arallel  and  facing  in 
the  same  direction.  As  I  saw  them,  eleven  years  after  their  formation,  they 
appeared  little  fresher  than  some  of  the  Wasatch  scarps. 

The  earthquake  that  shook  Sonora  and  southern  Arizona  on  the  third 
of  May,  1887,  produced  a  fault  scarp  which  Avas  critically  examined  by 
Goodfellow  and  traced  for  a  distance  of  35  miles.  It  intersects  the  alluvium 
along  the  base  of  a  mountain  range  or  ranges,  and  has  an  average  height 
of  seven  feet.  Like  the  Wasatch  scarp,  it  is  often  divided  or  furnished  with 
branches,  but  ludike  that  of  the  Wasatch  it  is  exceptionally  small  where  it . 
intersects  the  alluvia  of  streams  issuing  from  the  mountains.^ 

The  association  of  earthquakes  with  fault  scar])s  has  likewise  been 
determined  in  New  Zealand,  where  McKay  and  Hector  not  merely  refer 
certain  scarps  to  earthquakes  of  the  years  1848  and  l^f)b,  but  recognize 
them  as  the  indices  of  modern  slip.s  on  old  planes  of  dislocation,  and  use 
them  in  tracing  out  important  structure  features.'' 

-  It  is  legitimate  to  infer  that  the  belt  of  fertile  vallevs  tliat  follows  the 
western  base  of  the  great  mountain  range  of  Utah  is  an  earthquake  district, 
and  this  despite  the  feet  that  since  its  first  settlement  in  18.'')0  no  impoitant 
tremors  have  been  recorded.  It  is  a  matter  of  geologic  history  that  the 
Wasatch  range  is  gradually  rising,  and  that  this  rise  is  not  uniform  in  time 

■George  E.  Goodfellow.     The  .Sonora  Eartli(|u.ake;     Scieuce.  vol.  11,  p.  102. 

''Oil  the  geology  of  tlie  eastern  part  of  Marlborough  Provincial  district.  By  Alexander  McKay. 
In  Colonial  Mns.  and  Geol.  snrvey  of  New  Zealand  ;  Keports  of  Geological  explorations  during  lo85. 
Faults  on  pp.  129-133.     Also  James  Hector,  in  same  volume,  p.  xv. 


362  LAKE  BONNEVILLE. 

and  place,  but  is  accom})lishe(l  by  small  and  sudden  displacements  more  or 
less  localize<l,  with  intervals  of  rest.  Of  the  lengths  of  these  intervals  we 
have  no  means  of  judging-,  and  no  one  can  predict  the  date  of  the  next 
movement,  but  it  is  beyond  (piestion  that  such  iiiovement  will  take  ])lace, 
and  that  when  it  occurs,  the  adjacent  valley  will  experience  an  earthcjuake. 
Neither  is  it  possible  to  predict  with  great  confidence  what  portion  of  the 
district  will  be  next  affected,  but  if  the  orogenic  force  is  approximately  con- 
stant and  the  rhythm  in  its  visible  work  is  due  to  the  necessity  for  accumu- 
lated energy  to  overcome  friction,  then  the  localities  with  fresh  fault  scarps 
may  reasonably  be  assumed  to  be  exempt  from  faulting  for  a  longer  period 
than  those  in  which  onl)-  ancient  fault  scarps  are  seen.  Reasoning  thus,  I 
was  led  to  sound  a  note  of  warning  in  Salt  Lake  City,  which  stands  close 
by  an  exceptional  section  of  the  range,  where  the  fault  scarps  are  so  ancient 
as  to  be  largely  obliterated.^  Its  situation  with  reference  to  the  growing 
Wasatch  is  identical  Avith  that  of  Lone  Pine  with  reference  to  the  growing 
Sierra  Nevada,  and  it  is  largely  built  of  adobe,  a  material  ill  suited  to  with- 
stand earthquake  shocks.  In  the  village  of  Lone  Pine  every  house  was 
thrown  down  by  the  shock  of  1872,  and  27  persons  lost  their  lives, — a  literal 
decimation  of  the  population.^ 

The  relation  of  joints  to  the  earthquakes  of  the  Bonneville  Basin  is 
discussed  in  the  closing  paragraphs  of  Chapter  V. 

EVIDENCE  FROM  SHORE-IilNES. 

MEASUREMENTS. 

The  first  precise  determination  of  the  height  of  the  Bonneville  shore- 
line above  the  modern  lake  was  made  by  the  Wheeler  Survey  in  1X72,  a 
line  of  levels  being  run  from  Great  Salt  Lake  to  the  old  water  mark  against 
the  Wasatch  range  near  Fort  Douglas.  In  the  same  year  Ilowcll  of  that 
coi-ps  observed  the  barometer  on  what  was  supposed  to  be  the  .same  shore- 
line at  various  points  in  the  southern  part  of  the  Escalante  Desert.     The 

'The  warning  was  embodied  in  a  letter  to  the  Salt  Lake  City  Tribune  of  September 20,  188:!, 
afterward  ropriiited  in  the  American  Journal  of  Science,  'id  .series,  vol.  27,  January,  188-1,  pp.  ■I'.*-.'iX 

-I  iino'.e  these  (iKiiros  from  J.  D.  Whitney,  who  visited  Owen's  Valley  a  tew  weeks  after  the 
sliock  and  pnblished  a  careful  and  hijjhly  valuable  description  of  the  phenomena.  "The  Owen's  Val- 
ley Earthquake",  Overland  Monthly,  vol.  9,  16"'.',  pp.  130-140  and  2C6-'278. 


ESCALANTE  BAY.  363 

altitudes  deduced  from  liis  observations  were  about  300  feet  iiiolier  than 
tlie  altitude  at  Fort  Douglas.  Unfortunately,  the  barometric  result  was 
not  entitled  to  gi'eat  confidence,  so  that  only  a  presumption  of  difference  of 
altitude  was  established;  but  this  presumption  gave  rise  to  two  hypotheses, 
which  served  in  turn  to  direct  subsetpient  investigation.  It  was  surmised 
by  Howell  and  the  writer  that  changes  might  have  occurred,  since  the  epoch 
of  the  shore-line,^  in  the  actual  and  relative  altitudes  of  the  diflierent  points 
measured,  and  it  was  suggested  by  King  that  the  shore-line  in  the  P^sca- 
lante  Basin  might  be  found  to  belong  to  an  independent  lake,  higher  than 
Lake  Bonneville  and  tributary  to  it.^ 

Kin"''s  suggestion  led  to  a  careful  examination  of  the  strait  connectine: 
Escalante  Bay  with  the  Sevier  body  of  the  old  lake,  and  to  the  determina- 
tion that  it  did  not  contain  a  river  channel,  but  was  occupied  by  standing- 
water  with  an  approximate  dej)tli  of  50  feet,  and  a  width  at  the  most  con- 
stricted point  of  about  2  miles.  As  will  appear  in  a  subsequent  paragraph, 
the  synchronism  of  the  Escalante  shore-line  with  the  Bonneville  shore-line 
of  the  more  northerly  basin  has  not  been  established,  though  the  observation 
at  the  strait  renders  it  clear  that  the  body  of  water  occupying  the  Esca- 
lante Desert  was  continuous  with  a  body  of  water  in  the  deeper  basins  at 
the  north. 

The  idea  that  changes  in  altitude  have  supervened  since  the  production 
of  the  Bonneville  shore-line,  opened  a  most  attractive  field  of  investigation, 
for  it  seemed  possible  by  measuring  the  height  of  the  old  shore-lines  at  many 
points  to  obtain  definite  knowledge  of  the  amount  and  distribution  of  the 
post-Bonneville  displacements  of  the  earth's  crust  in  the  lake  area.  Earlier 
quantitative  studies  of  upheaval  and  subsidence  had  been  practically 
restricted  to  the  sea  coast,  because  there  the  ocean  affords  a  datum  plane 
fpr  measurement;  but  here  was  an  oppt)rtunity  to  pursue  similar  inquiries 
in  an  interior  district. 

In  subsequent  work  every  opportunity  was  improved  for  the  deter- 
mination of  the  present  height  of  the  records  of  its  water  surface.  Meas- 
urements were  made  with  the  engineer's  level  at  points  where  the  water  of 
Great  Salt  Lake  could  be  conveniently  used  as  a  datum  plane,  and  other 


'Survey  west  of  the  100th  meridian,  vol.  :!,  (i.  93.  'Geo!.  Expl.  40th  paralli'l,  vol.  1,  p.  491. 


364  LAKE  BONNEVILLE. 

measurements  where  the  same  purpose  was  served  by  points  on  raih-oads. 
At  a  few  pohits  Locke's  hand  level  mounted  on  a  , Jacob's  staff  was  the 
instrument  used,  and  at  other  points  triangulation  w;is  cnijjloycd  with  meas- 
ured base  lines.  In  some  regions  remote  from  good  points  of  reference, 
iind  especially  in  the  Escalante  Desei-t,  the  ])arometer  was  emjdoyed. 
S])irit-level  determinations  were  made,  not  oidy  of  the  height  of  the  I'onne- 
ville  shore-line,  but  of  the  I'rovo.  The  local  difference  between  the  two 
was  also  measured  at  some  points  where  neither  could  l)e  refeiTed  to  Great 
Salt  Lake.  For  the  purposes  of  the  investigation  the  altitudes  of  these 
various  points  above  the  sea  are  iniimportant,  since  <^>nly  their  relations  to 
one  another  can  be  discussed,  and  it  has  been  found  convenient  to  refer 
them  all  to  the  water  surface  of  Great  Salt  Lake ;  and  since  that  surface  is  a 
fluctuating  one,  a  particular  point  has  been  arbitrarily  assumed  within  the 
range  of  modern  fluctuation.  That  point  is  the  zero  of  the  "Lake  Shore" 
gauge.  As  the  relation  of  the  altitudes  to  sea  level  will  not  be  again  refer- 
red to,  it  is  proper  to  say  here  that  the  zero  of  the  "Lake  Shore"  gauge 
is  95  feet  lower  than  the  track  of  the  Pacific  Railroad  at  Ogden,  and  4,208 
feet  higher  than  mean  tide.  The  implied  altitude  of  Ogden,  4,303  feet,  is 
that  accepted  by  Gannett  in  his  dictionary  f)f  altitudes.^ 

As  the  various  measurements  employing  the  water  of  Great  Salt  Lake 
as  a  datum  were  executed  on  different  days  and  in  diff'erent  years,  it  was 
necessary  to  take  account  of  the  fluctuations  of  the  lake  surface,  and  this 
was  done  by  means  of  the  series  of  gauge  observations  already  described 
(see  page  233). 

A  more  important  difficulty  was  encountered  in  connecting  the  lines  of 
leveling  with  the  plane  of  the  f»ld  water  surface,  for  it  was  never  ])ossible 
to  decide  just  how  the  mean  level  of  the  old  water  surface  was  related  to  a 
particular  feature  of  its  shore  record.  At  some  ])laces  the  measurement 
was  made  to  a  cut-terrace,  and  at  others  to  an  eml)ankm('nt,  niid  wherever 
both  these  were  found  in  juxtaposition  and  measured,  it  was  ascertained 
that  the  embankment  stood  higher  than  any  ])art  of  the  cut-terrace.  It 
was  found,  moreover,  that  the  diflerence  between  these  twt)  features  was 


'A  Dictionary  of  Altitudes  in  the  Unitod  States,  compiled  by  Henry  Oannett:  Bull.  T'.  S.  Geol. 
Survey  No.  5.     1884. 


ALTITUDE  MEASUREMENTS. 


365 


less  in  sheltered  localities  than  on  coasts  facing  the  open  lake,  where  the 
fetch  of  the  waves  was  great.  The  inference  of  tW,  phuu!  of  tlie  ^\■at(•r 
surface  drawn  from  tlie  local  shore  record  wns  thus  necessaril\-  n  inatfer  of 
judgment,  and  tliis  judgment  was  usually  exercised  upon  llie  gniund,  wliere 
the  most  .satisfactory  consideration  could  be  given  to  the  local  conditions. 
Despite  all  precautions,  an  uncertainty  of  several  feet  attaches  to  each  such 
determination,  and  tliis  uncertainty  is  iiu'luded  in  the  estimation  of  llie 
probable  errors  of  the  measurements  of  altitude. 

Most  of  the  barometric  observations  and  all  the  l^arometric  computa- 
tions were  made  by  Mr.  A.  L.  Webster.  He  has  also  combined,  unified, 
and  tabulated  all  the  determinations  of  altitude,  and  has  prepared  a  report 
upon  them  which  appears  (Appendix  A)  at  the  end  of  this  volume.  For  all 
matters  of  detail  the  critical  reader  is  referred  to  his  report. 

DEFORMATION   OF  THE  BONNEVILLE  SHORE-LINE. 

A  summary  of  the  measurements  is  contained  in  tables  XIII,  XIV, 
and  XV,  and  their  geographical  distribution  is  indicated  to  the  eye  in  Pis. 
XLVI,  XLVII  and  XLVIII.  Attention  wdll  first  be  directed  to  the  table 
and  plate  which  exhibit  the  measured  altitudes  of  the  highest  Avater  line. 

Table  XIII. — Height  of  the  BonveviUe  Shore-line,  at  varioiin  2)oi>ils,  above  Great  Salt  Lulce  {Zero  of  "Lake 

Shore"  gauge). 


Locality. 


1.  Sautaqiiiii,  south  of  Utah  Lake 

2.  Leuiiuj;tou,  U.  S.  K.  U 

3.  Milfonl,  U.S.  R.  R  

4.  Red  Rock  Vass,  north  end  of  Cache  Valley   

T).  Franklin,  CJaehe  Valley 

li.  Logan,  Caeho  Valley 

7.  Point  of  the  Monntain;  22  niile.s  south  ol'  Salt  Lake  City 

8.  Ogden 

9.  Fort  Douglas,  near  Salt  Lake  City 

10.  Tecouia,  Nevada 

11.  Willard,  east  shore  of  Great  Salt  Lake 

12.  Black  Rock,  north  end  of  Oquirrh  Range 

13.  Stockton,  head  of  Tooele  Valley 

14.  Kelton  Butte,  near  Onibe  Station.  C.  P.  R.  R 


Height. 


Feet. 
902  -(-  3 
902  -t  5 
904  i  10 
900  ±  4 
940  -I-  3 
942  i  4 
9.'30  ±  3 
980  4-5 

980  ±5 

981  ±5 
98.1  ±  3 

1008  ±  3 
1014  ±5 
1019  ±  3 


366 


LAKE  BONNEVILLE. 


Table  XUl.—Bcight  of  Ihe  Bonnerille  Shore-line,  at  varioux  pohilH,  above  Great  Salt  Lake  (Zero  of  "  Lake 

Sliore"  gauge) — Coutiniied. 


Locality. 


iri.  Promontory,  10  miles  south  of  Promontory  Rtatlon,  C.  P.  R.  R 
If).  North  end  of  Aqiii  range;  12  miles  northwest  of  Grantsville... 

17.  Two  niile.s  east  of  Thermos  Spring,  Escalante  Desert 

H.  Pavant  Hnttc,  Sevier  Desert 

19.  Seven  miles  sontli  of  Mil  ford 

20.  Four  miles  south  of  Thermos  Spring,  Escalante  Desert 

21.  Seven  niiU>s  south  of  Thermos  Spring,  Escalante  Desert 

22.  Fillmore,  east  edge  of  Sevier  Desert 

23.  South  Twin  Peali,  south  end  of  Sevier  Desert 

24.  Kanosh  Butte,  south  end  of  Sevier  Desert 

25.  North  Twin  Peak,  south  end  of  Sevier  Desert 

2G.  Antelope  Spring,  Escalante  Desert 

27.  Sulphur  Spring,  Escalante  Desert 

28.  Pinto  Canyon,  Piscalaute  Desert 

29.  Shoal  Creek  Canyon,  Escalante  Desert 

30.  Meadow  Cieek  Canyon,  Escalante  Desert 


Height. 


Feet. 

10.^0  -t  3 

1070  -{-  3 

893  ±  2.5 

902  J-  15 

921  ±  20 

921  ±  25 

927  i  25 

938-1-8 

9.39  ±  20 

953  -t  15 

971  ±20 

1008  ±  30 

101.-)  -J-  25 

1175  ±  35 

1227  ±  35 

1256  ±35 

It  appears  by  inspection  that  the  range  of  ahitude  is  about  350  feet, 
the  determination  of  the  amount  having  an  uncertainty  of  less  than  50  feet. 
The  distribution  of  altitudes  does  not  follow  any  simple  law,  l)ut  yet  exhil)- 
its  certain  general  features.  There  appear  to  be  two  areas  in  which  the 
water  mark  is  especially  high,  the  first  coinciding  approximately  with  the 
central  meridian  of  Great  Salt  Lake,  and  the  second  occupying  the  Esca- 
lante Desei't,  especially  its  southern  portion.  Along  tlie  eastern  border  of 
the  basin,  from  the  extreme  north  to  the  extreme  south,  there  is  a  general 
increase  of  altitude  from  east  to  west.  At  the  south  this  is  continued  west- 
ward to  the  limit  of  the  area  covered  by  the  observations,  ami  is  greatly 
accented.  At  the  north,  where  the  observations  have  the  greatest  range  in 
loiiiritude,  the  westward  rise  is  rcijhu'cd  bcNoiid  tlie  I'l-oiiiontorv  Ivauiic  bv 
a  westward  decline.  It  ap])ears,  moreover,  that  to  ;ill  tliese  general  ruU's 
there  are  local  exceptions,  and  that  where  a  rise  in  a  certain  direction  i.-< 
continuously  indicated  by  a  series  of  localities,  its  rate  from  point  to  j)oint 
is  not  unifonu. 


DISPLACEMENTS  OF  BONNEVILLE  SHORE-LIN^,. 


367 


A  comparison  of  the  measured  heights  of  shore-hne  with  the  system  of 
faults  in  the  same  region  indicates  in  general  that  they  are  not  closely 
related,  and  in  particular  that  the  faults  cannot  be  appealed  to  as  a  suffi- 
cient explanation  of  the  displacements  of  the  shoi'e-line.  A  good  illustra- 
tion of  this  is  found  in  the  latitude  of  Salt  Lake  City,  where  the  height  of 
the  shore-line  has  been  measured  on  three  adjacent  parallel  ranges.  On  the 
Wasatch  it  is  DSO  feet,  on  the  (Jquirrh  1,008  feet,  and  on  the  Aqui  1,070 
feet.  Now  each  of  these  ranges  has  suffered  a  post-Bonneville  faulting  at 
its  western  margin,  as  represented  in  Fig.  49,  and  the  throw  of  each  fault  is 
to  the  west.     The  eft'ect  of  these  faults,  if  there  were  no  other  diastrophic 


V. 

A 

T 

A 

si 

h 

•^               / 

\ 

TOOELE   VALLEY 

/ 

,\ 

JORP  A  tJ 

VA 

LLEY 

% 

=5  5       / 

/ 

t  \ 

o 

5  S      / 

0:       \ 

/ 

or 

V__^ 

5 

v__ 

i 

K    1 

h. 

?lf 

?| 

cj 

\ 

Fig.  49.— Generalized  cross-profilo  of  mountains  and  valleys,  illustrating  post-Bonneville  dia3troi)bic  ( hanges.  Ver- 
tical scale  greatly  exaggerated.  Lower  liorizontal  lino  =  level  of  Great  Salt  Lake.  Dotted  line  =  1,000  feet  above  Great 
Salt  Lake.     Y  T  &  =  Bonneville  shore-line. 

changes,  would  be  to  lift  the  Wasatch  higher  than  the  Oquirrh,  and  both 
higher  than  the  Aqui,  but  the  shore  measurements  show  the  reverse  of  this. 
If  we  assume  that  the  portion  of  the  earth's  crust  included  between  each 
pair  of  the  observed  faults  is  rigid,  so  as  to  move  as  a  unit  without  flexure, 
then  the  post-Bonneville  changes  determined  l)v  the  observations  on  faults 
and  shore-lines  are  correctly  represented  (except  in  exaggeration  of  vertical 
scale)  in  fig.  50,  where  the  base  line  indicates  the  level  of  Great  Salt  Lake, 


Fir;.  50. — Diaj;ran»  of  po-st-Roiineville  tii;istropliic  changes.  Easo  line  —  level  or  (tftat  Suit  I,jiK<^.  l*<itt(Ml  Hue  ~  nrijr 
iiinl  position  of  plane  <)f  Komievillo  sliore-liiir.  Inclined  linea  =:  present  jiosition  of  same  plane.  *4  O  TT^  positions  of 
Aqui,  Oquirrh  and  Waaatch  Ranges. 

the  dotted  line  parallel  to  it  represents  the  original  horizon  (»f  the  Bonneville 
sliore-line,  assumed  to  be  marked  in  some  way  on  the  orogenic  block,  and 


368  LAKE  BONNEVILLE. 

the  sloping'  lines  represent  the  position  the  sliore-line  has  assumed  by  dias- 
trophic  flianges  since  tlie  Bonneville  epoch.  Tin-  indication  is  that  each 
erogenic  block  is  canted  to  tlu;  eastward  (riglit),  and  that  eacli  block  con- 
sidered as  a  whole  stands  liigher  than  its  eastern  neighbor,  notwithstanding 
its  relative  depression  along-  the  plane  of  contact.  It'  the  })henomena  of  tliis 
group  of  localities  were  general,  we  should  have  an  exceedingly  interesting 
relation  between  the  general  deformation  of  the  shore-line  and  the  system 
of  faults;  but  they  are  not  general,  and  we  can  only  say  that  the  principal 
diversities  of  shore-line  altitude  ap})ear  to  be  independent  of,  and  otten  in 
spite  of,  changes  by  faulting.  The  changes  revealed  l)y  tlie  measurement 
of  shore-lines  affect  broad  areas,  and  are  essentially  epeirogenic,  while  those 
demonstrated  by  the  favdt  scarps  are  definitely  associated  with  mountain 
ranges,  and  are  orogenic.  The  shore-lines  are  indeed  deformed  by  both  sj's- 
tems  of  disturbance,  but  the  epeirogenic  are  the  greater.  Just  as  the  Great 
Basin  is  characterized  by  bi'oad  epeirogenic  undulations,  dividing  it  into  a 
series  of  minor  basins,  and  by  relatively  narrow  mountain  corrugations, 
Avhicli  rest  upon  the  broader  undulations  like  rijjples  on  the  ocean  wave,  so  I 
conceive  the  post-Bonneville  epeirogenic  displacements  to  be  the  greater  of 
the  features  represented  by  the  deformation  of  the  shore-lines,  and  the  oro- 
genic displacements  to  cond^ine  with  them  as  local  details  or  irregularities, 
it  would  be  desirable  from  this  point  of  view  to  eliminate  the  orogenic 
factor  and  study  the  epirogenic  changes  by  themselves,  but  our  knowledge 
of  the  fault  system  is  too  imperfect  to  permit  this,  and  it  will  therefore  be 
assumed,  somewhat  arbitrarily,  that  the  e])irogenic  undulations  are  smoother 
and  simpler  than  the  measurements  would  indicate,  the  a])])arent  iiregidar- 
ities  Ijciny  due  to  local  faultin"'  as  well  as  to  errors  of  measurement.  ( )n 
the  basis  of  tliis  assumption  isogrammic  Hues  have  been  drawn  on  Plate 
XLVI,  connecting,  so  far  as  possible,  points  at  wliicli  the  l!oniK\  illc  sliorc- 
linc  has  now  the  same  altitude.  Tliey  art^  drawn  at  ccpial  inti'rvals  of  100 
feet,  and  serve  to  express  in  another  way  the  general  featin-cs  of  distribu- 
tion of  altitude  described  above.  If  we  conceive  of  the  plane  of  tlie  ancient 
water  surface,  both  actual  and  ideally  projected  through  the  contiguous 
land,  as  having  been  deformed  by  subsequent  epeirogenic  changes,  then 
these  lines  are  contours  on  the  deformed  surface. 


U.S. GEOLOGICAL   SURVEY 


LAKE  BONNE'/ILLE      PL.2EVI 


111 


JuJiim  Bien  ftCb.lilh 


DtawB  bv  G  Thompst 


SYNCHRONISM  OF  BONNEVILLE  SBOliB-LINE.  369 

It  has  been  tacitly  assumed  up  to  tliis  point  tliat  all  these  measurements 
of  the  Bonneville  shore-line  relate  to  the  same  e|)0('li,  or,  in  other  woi-ds,  that 
the  various  sections  of  the  highest  shore  mark  in  all  jiarts  of  the  basin  were 
formed  at  the  same  time;  but  in  view  of  the  demonstrated  mutability  of  the 
land  surface  on  which  the  water  marks  are  traced,  this  assumption  is  mani- 
festly open  to  question.  It  may  well  have  Imppened  that  at  one  high  stage 
of  ^yater  in  the  basin  the  maximum  water  line  was  scored  upon  a  land  surf;i,ce 
in  one  attitude,  and  at  the  following  high  stage  upon  the  same  land  surface 
in  a  different  attitude,  and  that  the  two  water  lines  severally  reached  their 
greatest  heights  on  the  land  at  different  points.  Tlie  highest  water  line  in 
one  part  of  the  area  would  then  re[)resent  one  tlood  stage  and  elseAvhere  the 
other,  so  that  the  maxinmm  line  as  a  whole  would  not  be  synchronous.  It 
might  also  happen  that  during  tlie  maintenance  of  one  high  stage  changes 
would  occur  in  the  relative  height  of  different  portions  of  the  land,  causing 
some  parts  to  emerge  and  others  to  become  more  deeply  submerged.  This 
also  would  produce  a  lack  of  synchronism  in  the  highest  shore-line.  The 
questions  arising  from  these  possibilities  must  in  general  be  difficult  of 
solution,  but  in  the  case  of  the  Bonneville  shore-line  we  fortunately  have  a 
test  of  wide  application.  The  reader  will  recall  that  in  the  detailed  account 
of  the  shore  there  were  described  a  number  of  series  of  bars  differing  by  a 
few  feet  in  height,  and  demonstrating  that  just  previous  to  the  establish- 
ment of  the  outlet  the  lake  surface  had  undergone  a  corresponding  series  of 
oscillations.  A  comparative  study  of  these  systems  of  bars  showed  that  the 
oscillations  had  been  essentially  the  same  at  all  localities,  and  it  is  thus 
known  that  throughout  the  area  of  their  occurrence  the  shore-line  belonjrs 
to  the  same  high-water  stage.  The  demonstration  applies  to  the  entire 
main  body  of  the  lake  and  its  principal  dependencies,  and  to  the  Sevier 
body  and  Preuss  Bay,  but  it  does  not  a.pi)ly  to  Escalante  Bay.  Tlie  most 
southerly  points  at  which  the  peculiar  bar  system  was  observed  lie  in 
latitude  38°  40'.  The  lack  of  positive  data  in  the  region  of  the  Escalante 
Desert  is  not  of  great  significance,  for  opj)ortunities  for  observing  this  spe- 
cial feature  are  everywhere  rare,  and  there  would  be  no  reason  for  giving 
special  consideration  to  that  region  in  this  connection,  were  it  not  that  the 
displacements  there  exhibited  are  of  exceptional  magnitude.  The  crowd- 
MON  I 24 


370 


LA. KB  BONNEVILLE. 


ing  together  of  the  contours  of  deformation  in  that  region  suggests  tliat  the 
epeirogenic  forces  may  there  hnvc  liad  a  hunger  period  for  the  accunudation 
of  their  results,  and  raises  tlie  ([uestion  whether  the  Escalante  Desert  may 
not  liave  received  an  arm  of  the  lake  during  its  first  period  of  flood,  and 
then  have  been  so  greatly  elevated  as  to  remain  dry  during  the  period  of 
the  second  flood.  The  only  evidence  that  can  be  brought  to  bear  upon 
this  question  without  new  field  work  is  obtained  by  comparing  tlie  Escalante 
shore  record,  as  to  state  of  preservation  and  strength,  with  the  records  in 
other  valleys  of  similar  character.  Mr.  Howell  and  Mr.  Webster,  who  were 
the  chief  observers  of  the  Escalante  shore,  both  report  it  as  faint  and  diffi- 
cult of  determination,  and  my  own  observations,  limited  to  a  few  localities 
only,  confirm  their  report.  The  best  region  for  comparison  is  Snake  Valley, 
where,  as  in  the  Escalante  Desert,  the  bay  was  shallow  as  well  as  narrow, 
and  judging  from  my  own  observations,  the  Snake  Bay  shore  record  is 
notably  more  conspicuous  than  that  of  Escalante  Bay. 

In  view  of  these  considerations  the  Escalante  data  will  be  disregarded 
in  the  subsequent  discussion  of  the  deformation  of  the  Bonneville  shore. 

Table  XIV. — Height  of  the  Provo  shore-line,  at  various  points,  above  Great  Salt  Lake  (Zero  of  ''Lake  Shore" 

gauge). 


Locality. 


1.  White  Mountain  spring,  e.asl  side  of  Sevier  Desert 

'2.  Franklin,  Caclii'  Valley 

3.  Logan,  Ciche  Valley 

4.  Point  of  the  Mountain  ;  22  miles  sonth  of  Salt  Lake  City 

5.  Will.ird,  east  shore  of  Gre.it  Salt  Lake 

6.  Black  Eock,  north  end  of  Oquirrh  Range 

7.  Tooele  Valley  between  Tooele  .and  Stockton 

8.  Kolton  Butte,  near  Onil)e  st.ation,  C.  P.  K.  R 

9.  Promontory,  10  miles  south  of  Promontory  station,  C.  P.  R.  R 
10.  North  end  of  Aqni  Range;  12  miles  northwest  of  Grantsville  . 


Height. 


Feel. 

553  ± 

10 

5G9  ± 

^ 

577-1- 

2 

580-1- 

3 

624  ± 

5 

640  ± 

4 

(i40  -t 

5 

r>(i3  -t 

3 

672  ± 

3 

679  ± 

3 

ESCALANTE  BAY.  371 

DEFORMATION  OF  THE  PROVO  SHORE-LINE. 

We  will  now  turn  to  the  consideration  of  Table  XIV  and  PI.  XLVII, 
which  record  in  their  several  ways  the  various  determinations  of  the  heig'ht 
of  the  Provo  shore-line.  The  special  criterion  by  which  the  identity  and 
synchronism  of  the  Bonneville  shore-line  were  established  throughout  the 
greater  part  of  the  liasin  cannot  be  applied  in  the  case  of  the  Provo. 
Where  the  embankments  successively  formed  during  Provo  time  are  sepa- 
rated from  one  another  so  as  to  be  independently  measured,  they  exhibit 
differences  of  height,  but  these  diiferences  are  neither  uniform  nor  constant 
at  the  various  localities  where  they  were  observed.  The  conclusion  has 
already  been  reached  (page  133)  that  there  were  changes  of  relative  height 
while  the  wave  record  was  being  made.  Nevertheless,  it  was  always  easy 
to  recognize  the  Provo  shore-line  and  discriminate  it  from  others  by  reason 
of  the  exceptional  magnitude  of  the  wave  work  accomplished  at  that  level. 
The  cut  terraces  are  broader  than  any  other  within  the  basin,  and  the 
embankments  are  larger.  At  most  points  it  is  impossible  to  determine  from 
the  features  of  the  shore  what  was  the  local  history  of  oscillation  during  the 
persistence  of  the  outlet,  for  the  later  work  of  the  waves  has  effectually 
obliterated  the  earlier.  It  is  highly  probable  that  those  of  its  features  to 
which  measurement  was  extended  represent  the  final  portion  of  the  long 
period  during  which  the  water  stood  at  approximately  the  same  height. 

The  number  of  measurements  is  smaller  than  in  the  case  of  the  Bonne- 
ville shore-line,  only  10  having  been  secured;  but  these  are  so  much  more 
harmonious  that  it  was  found  possible  to  draw  a  system  of  smooth  contours 
representing  intervals  of  25  feet  only.  A  comparison  of  Pis.  XLVI  and 
XLVII  shows  at  a  glance  that  these  correspond  in  position  and  arrange- 
ment with  the  contours  adjusted  to  the  Boinieville  data  in  the  same  area. 
The  area  of  maximum  elevation  indicated  by  them  lies  over  the  western 
portion  of  Great  Salt  Lake.  There  is  a  descent  thence  to  the  east,  and 
more  gently  to  the  southwest  and  south,  while  a  single  station  indicates 
descent  to  the  northwest  also. 


372 


LAKE  BONNEVILLE. 


Table  XV. — Difference  in  altitude  of  the  Bonneville  and  I'rovo  shore-lines  at  various  points. 


Locality. 


Prciiss  valley,  South  series  of  embankments 

Preuss  valley,  Middle  series  of  embankments , 

Kelton  Butte,  near  Ombe  Station,  C.  P.  R.  R 

Black  Rock,  north  end  of  Oquirrh  Range 

Willard,  east  shore  of  Great  Salt  Lake 

Snowsville,  north  edge  of  Great  Salt  Lake  Desert 

Logan,  Cache  Valley 

Point  of  the  Mountain,  22  miles  south  of  Salt  Lake  City 

Franklin,  Cache  Valley 

Promontory,  10  miles  south  of  Promontory  Station,  C.  P.  R.  R 

Tooelo  Valley  between  Tooele  and  Stockton 

Tooelo  Valley  between  Tooele  and  Grantsville 

Wellsville,  Cache  Valley 

Fish  Spring,  south  edge  of  Great  Salt  Lake  Desert 

Fillmore,  east  edge  of  Sevier  Desert 

North  end  of  Aqui  Range;  12  miles  northwest  of  Grantsville 

Cup  Butte,  Old  River  Bed 

Suowplow,  Old  River  Bed 

Terrace  Mts.,  8  miles  southeast  of  Matlin  Station,  C.  P.  R.  R 

Dove  Creek,  between  Matlin  and  Ombe,  C.  P.  R.  R 


Height. 


Feet. 
311  ± 

345± 

3o6-|- 

360 -J- 

361  i 

360-1- 

^r,r,  ± 

370 -t 

371  -t 

374  J- 

374-1- 

380 -t 

382  ± 

382  ± 

385-1- 

389  i 

392  i 

397  -t 

411-1- 

413  ± 


DEFORMATION  DURING  THE  PROVO  EPOCH. 

Table  XV  and  PI.  XLVIII  show  the  measured  differences  in  aUitude 
of  the  Bonneville  and  Provo  shore-lines  at  various  points.  The  localities  at 
which  these  differences  were  measured  coincide  partly  with  localities  of  the 
two  ])receding  tables,  but  are  also  in  part  independent;  for  it  was  sometimes 
found  possible  to  make  the  differential  measurement  where  tlie  lack  of  an 
available  datum  point  prevented  the  reference  of  either  to  the  level  of 
Great  Salt  Lake. 

The  range  of  variation  is  not  large,  and  whatever  order  mi\\  charac- 
terize them  is  so  far  concealed  by  irregularities  that  it  was  found  impossible 
to  classify  them  by  any  system  of  smootli  contours.  Ikit,  as  will  j)resently 
appear,  when  they  are  classified  with  reference  to  the  contours  of  the  IJon- 
neville  and  Provo  .shore-lines,  thev  betray  a  certain  amount  of  harmonv. 

It  will  be  recalled  that  when  the  lake  attain<Ml  its  maxiniuni  height  and 
outflowed,  the  water  was  discharged  witii  great  raj)idity  down  to  the  level 


U  S. GEOLOGICAL    SUF^/EY 


L/a<.E   'BO^U'IE'.ILI.K      PI ,.  XLVJJ 


112° 


iir 


-  a" 


MAP  OF 

LAKE  BONNEVILLE 

shoT.\'inq 
THK    DEP^OR^L\TION 

OF     THE 

PROVO   SHORE Li:s'E 

thl;  i^(isiti(-)N  of  cheat  s.\lt  lake 
on  tt.s  pi.mn 


42° 


Julius  Bien  iGi.lith 


Drawn  by  G  Thomps. 


us. GEOLOGICAL   SURVEY 


LAKE  BONNEVILLE      PL.  XLViR 


LAKE  BONNEVILLE 

showing 
local  variations  of  the 

VPJRTICAL  INTERVAL 

between  iKe 

BONNEVILLE  AND   PROVO 
SHORELINES 


red  Figures  indicate 
ences  of  altitude  in  feet 


j  Miles. 


Julms  Hieii  ftCo.hih 


Dravrn  hv  C  Tliumpsoti 


DISPLACEMENTS  OF  THE  PKOVO  EPOUH,  373 

of  the  Provo  shore,  at  which  level  the  lake  stood  for  a  relatively  long  time. 
This  time  may  have  been  continuous  or  may  have  been  more  or  less  inter- 
rupted by  the  temporary  retreat  of  the  Avater  to  lower  levels.  Including 
such  interruptions,  if  any  occurred,  it  has  been  called  the  Provo  epoch. 
The  table  and  map  of  differences  between  the  Bonneville  and  Provo  shore- 
lines represent  the  changes  of  altitude  occurring  in  Provo  time,  or  from  the 
end  of  the  epoch  of  the  Bonneville  shore-line  to  the  end  of  the  Provo  epoch. 
The  diiferences  of  level  of  the  Provo  shore-line  represent  changes  wrought 
since  the  end  of  the  Provo  epoch,  and  those  of  the  Bonneville  shore-line 
changes  since  the  beginning  of  the  epoch  of  outflow. 

POSTULATE  AS  TO  CAUSE  OF  DEFORMATION. 

The  area  of  maximum  elevation,  as  indicated  by  these  data  from  the 
Bonneville  and  Provo  shore-lines,  coincides  with  the  middle  portion  of  the 
main  body  of  Lake  Bonneville;  and  this  coincidence  suggests  the  hypothesis 
that  the  disappearance  of  the  lake  and  the  epeirogenic  rise  of  the  center  of 
its  basin  stand  in  the  relation  of  cause  and  effect.  In  the  ensuing  discussion 
this  relation  will  be  postulated,  though  it  must  be  clearly  understood  that 
the  available  data  do  not  demonstrate  it,  but  merely  endow  it  with  a  certain 
degree  of  probability;  and  since  a  somewhat  elaborate  structui-e  will  be 
founded  upon  it,  it  is  especially  desirable  that  the  weakness  as  well  as  the 
strength  of  the  postulate  be  clearly  perceived 

The  postulate  is  in  some  sense  graphically  expressed  by  PI.  L,  where 
the  contour  lines  of  the  preceding  plates  are  so  modified  as  to  make  closed 
curves  repi'esenting  a  dome-like  figure  of  deformation,  slightly  elongated  in 
the  direction  of  the  axis  of  the  lake.  The  data  used  in  the  construction  of 
this  system  of  lines  are  selected  from  the  measurements  of  the  Bonneville 
shore-line,  excluding  all  that  depend  upon  Ijarometric  work — a  principle  of 
selection  which  omits  all  measurements  with  high  probable  error,  as  well  as 
tliose  made  in  the  Escalante  Desert,  which  are  independently  questionable. 

The  first  consideration  favoring  the  postulate  is  the  one  just  mentioned, 
that,  so  far  as  trustworthy  measurements  indicate,  the  area  of  maximum 
uplift  coincides  with  the  center  of  the  principal  area  of  deep  water  in  the 
old  lake. 


374 


LAKE  BONNEVILLE. 


A  second  favorable  consideration  arises  from  a  comparison  of  the  clianges 
occurring  severally  during  the  Provo  epoch  and  since  the  Provo  epoch  a\  ith 
the  total  changes  since  the  formation  of  the  Bonneville  shore-line.  To  make 
this  comparison,  the  various  measurements  were  classified  with  reference  to 
areas  marked  out  by  the  hypothetic  contours.  In  Table  XVI,  the  colunm 
of  figures  at  the  right  contains  measurements  of  the  height  of  each  shore- 
line and  of  their  difference,  so  far  as  these  were  measured  within  the  area 
circumscribed  by  the  1050-foot  contour.  The  next  column  at  the  left  con- 
tains the  measurements  made  at  localities  falling  within  the  area  limited  on 
one  side  by  that  contour  and  on  the  other  by  the  1000-foot  contour;  and 
so  for  the  remaining  two  columns. 


Table  XVI.  —  Comparison  of  post-BonneviUe,  post-Provo  and  Proi'o  Deformations  (fii/nres  yire  feet). 


Areas  between  contours  on  Plate  L 

900 
to 

9.''>0 

950 

to 

1000 

1000 

to 
1050 

1  Above 
1050 

Determinations  of  Bonneville  shore-liue  above 
Great  Salt  Lake ., 

(-     902 
902 
904 
906 
940 
942 

9.'j0 
965 
980 
981 

1008 
1014 
1019 
1050 

1070 

Mean                         .          ........      ....    .. 

916 

969 

1023 

1070 

Determiuations  of  Prove  shore-line 

Mean .- 

553 
569 
577 

580 
624 

640 
640 
663 
672 

679 

566 

602 

654 

679 

Determinations  of  difference  between  Bonne- 
ville and  Prove  shore-lines 

Mean        ... 

-     :J41 

345 

365 

-       371 

385 

361 
365 
370 
382 
382 
392 
397 

356 
360 
374 
374 
380 
411 
413 

389 

361 

378 

381 

389 

By  arranging  the  determinations  in  this  way  and  then  taking  means, 
it  was  hoped  to  eliminate  so  much  of  the  in-egularity  due  to  orogenic  dis- 


US  .GEOLOGICAL   SURVEY 


LAKE  BONNEVILLE      ?L:ZLI2 


US' 


113° 


n2° 


xa." 


Julius  Bien  it  Co.  lith 


Druwu  bv  C  Thompsc 


U.   S.   GEOLOGICAL  SURVEY 


LAKE  BONNEVILLE      PL.   L 


SCALE 


ILES 


THEORETIC  CURVES  OF   POST-BONNEVILLE   DEFORMATION. 


DESICCATION  AND  UPLIFT.  375 

placement  and  to  errors  of  measurement  as  to  render  the  data  fairly  com- 
parable. The  measurements  of  the  Bonneville  shore-line  having  been  used 
as  a  basis  for  th-awing  the  contours,  their  means,  as  a  matter  of  course, 
constitute  a  series;  and  it  was  anticipated  that  the  Provo  determinations, 
having  given  rise  on  PI.  XLVII  to  very  similar  contours,  would  likewise 
furnish,  as  they  do,  a  progressive  series  of  means;  but  a  similar  corre- 
spondence could  not  have  been  confidently  predicted  for  the  observations 
of  difference  in  altitude  of  the  two  shores,  for  these  are  so  irregular  in  detail 
that  representative  contours  could  not  be  drawn.  Nevertheless,  their  means 
as  thus  classified  fall  into  line  with  remarkable  regularity.  It  appears  to 
be  a  legitimate  inference  that  the  epeirogenic  deformation  occurring  during 
the  Provo  epoch  was  identical  in  locus  and  general  character  with  that 
occurring  subsequently,  and  with  the  total  deformation  of  which  it  is  a  part; 
and  this  accords  with  the  postulate,  for  if  the  withdrawal  of  the  entire  mass 
of  water  produced  the  quaquaversal  uparcliing  of  the  basin,  then  the  par- 
tial emptying  of  the  basin  by  the  draining  off  through  the  outlet  of  a  layer 
of  water  375  feet  deep  should  produce  a  similar  uparcliing,  differing  only 
in  amount. 

Opposed  to  the  postulate,  we  have  the  general  fact  that  the  Great 
Basin  appears  to  have  been  characterized  by  epeirogenic  movements,  varied 
in  character,  through  Tertiary  and  Pleistocene  time,  and  that  as  these  move- 
ments successively  created  and  destroyed  lake  basins,  they  must  be  sup- 
posed to  have  generally  originated  in  a  different  way.  It  is  therefore  pos- 
sible that  the  coincidence  in  time  and  place  of  the  uplift  under  consideration 
with  the  disappearance  of  Lake  Bonneville  is  a  coincidence  merely. 

A  second  and  very  serious  element  of  weakness  in  the  postulate 
inheres  in  the  fact  that  the  observations  are  mainly  confined  to  the  eastern 
lialf  of  the  basin.  Only  two  points  of  observation  lie  west  of  the  max- 
imum area,  and  only  one  measurement  was  made  in  the  extreme  western 
portion  of  the  basin.  The  area  well  covered  by  points  of  determination  is 
at  most  not  more  than  two-thirds  of  the  entire  area  to  which  the  postulate 
is  applied. 

These  considerations  pro  and  con  hardly  admit  of  explicit  summation. 
The  predilections  of  each  geological  reader  will  determine    the   relative 


376  LAKE  BONNEVILLE. 

weight  he  asisigns  to  them,  and  his  cniisoqneiit  confidence  or  lack  of  confi- 
dence in  the  conclusions  which  follow. 

There  are  at  least  three  ways  in  wliicli  the  removal  of  the  water  may 
have  given  rise  to  the  observed  variation  of  altitudes.  First,  the  geoid  may 
have  been  locally  deformed  by  a  change  in  the  local  attraction;  second, 
the  surface  of  the  laud  may  have  been  deformed  by  local  expansion  due  to 
the  post-Bonne ville  change  of  climate;  third,  the  earth  itself  may  have  been 
locally  deformed  in  consequence  of  the  removal  of  the  weight  of  the  water. 
These  three  hypotheses  will  be  considered  in  order;  and  it  will  be  found 
advantageous  to  inquire  Avith  reference  to  each  how  the  deformation  it  is 
competent  to  produce  compares  in  amount  with  the  observed  defoniintion. 
The  maximum  measure  of  the  observed  deformation  is  1070  — !M)2r=  l(>s 
feet;  but  as  this  may,  and  probably  does,  involve  local  orogenic  displace- 
ments, it  will  be  better  to  use  for  the  present  purpose  a  measure  obtained 
by  comparing  a  number  of  the  highest  measurements  collectively  with  a 
number  of  the  lowest.  The  mean  of  the  five  observations  of  height  falling 
within  the  1000-foot  contour  is  1032  feet.  The  mean  of  the  four  lowest 
determinations  is  903  feet,  and  their  difference,  121)  feet,  will  be  compared 
with  the  various  amounts  inferable  from  the  three  hypothetic  causes. 

HYPOTHESIS  OF  GEOIDAL  DEFORMATION. 

The  siu'face  of  a  body  of  standing  water  is  level,  but  is  not  plane. 
Being  a  part  of  the  surface  of  the  earth,  it  is  ai)proximately  ellipsoidal.  If 
there  were  no  inequalities  of  surface,  and  the  density  of  the  earth  were  uni- 
form throughout,  or  varied  only  in  accoi'dance  with  certain  laws,  a  level 
surface  carried  completely  around  the  globe  would  be  a  perfect  ellii)soid. 
The  actual  inequalities  of  surface  and  irregularities  of  density  produce  local 
irregularities  of  attraction  and  corresponding  irregularities  of  the  level  sur- 
face. To  distinguish  the  deformed  level  surface  from  the  s])heroid  to  which 
it  approximates  it  is  called  the  "gcoiil".  Any  change  in  tlie  superficial  dis- 
tribution of  matter  modifies  tlie  geoid,  and  tlie  i-einoval  ot  the  lake  water 
from  the  Bimneville  Basin  was  such  a  change.  The  effect  of  refilling  the 
basin  would  be  to  increase  the  local  attraction  and  locally  uparch  the  geoidal 


DEFOKMATION  OF  PLANE  OP  KEFEKENCE.         377 

surface;  its  emptying-  unquestionably  tended  to  flatten  the  geoidal  surface. 
Assuming  the  configiu-ation  of  the  country  unclaanged,  the  Bonneville  sur- 
fiice  was  more  sharply  convex  than  the  Salt  Lake  surface,  and  the  engineer's 
level  should  now  find  the  Bonneville  shore-line  higher  on  central  islands 
than  on  peripheral  slopes.  The  theoretic  change  corresponds  in  kind  with 
the  observed;  does  it  agree  in  amount?  My  mathematical  resources  not 
being  adequate  to  this  question,  it  was  submitted  to  my  colleague,  Mr.  R. 
S.  Woodward,  who  gave  it  full  consideration.  It  happened  that  tlie  cognate 
problem  of  the  deformation  of  the  geoid  by  a  continental  ice  mass  was  sub- 
mitted to  him  at  about  the  same  time  by  Dr.  T.  C  Chamberlin,  and  he 
was  thus  led  to  a  comprehensive  discussion  of  the  general  subject  to  which 
the  special  problems  belong.  In  the  application  of  his  formulfe  to  the 
present  case  no  account  was  taken  of  topographic  details,  but  the  mass  of 
water  in  the  main  body  of  Lake  Bonneville  was  assumed  to  have  the  form 
of  a  circular  lens  two  degrees  (138  miles)  in  diameter  with  a  maximum 
depth  of  1000  feet.  It  was  found  that  the  maximum  de^iression  of  the 
geoidal  surface  referable  to  the  subti'action  of  such  a  mass  is  2.01  feet,  an 
amount  too  small  to  be  considered  in  comparison  with  the  observed  deforma- 
tion of  129  feet.  The  phenomena  are  therefore  not  to  be  explained  as 
changes  in  the  plane  of  reference,  but  must  be  referred  to  changes  in  the 
relative  altitude  of  portions  of  the  basin. 

The  reader  will  hud  an  abstract  of  Mr.  Woodward's  treatment  of  the 
problem  in  Appendix  B. 

HYPOTHESIS  OF  EXPANSION  FROM  WARMING. 

The  second  hypothesis  involves  considei'ations  of  temperature.  The 
temperature  of  the  earth's  crust  at  the  surface  is  identical  with  the  mean 
annual  temperature  of  the  contiguous  fluid,  air  or  water,  and  at  all  subter- 
ranean points  it  is  warmer,  the  change  of  temperature  with  depth  being 
gradual.  Every  change  of  climate  prcxluces  a  corresponding  change  in  the 
sui-face  temperature  of  the  crust,  and  this  change  is  slowly  propagated  down- 
ward. When  the  Bonneville  Basin  was  full  of  water,  there  can  be  little 
question  that  the  surface  temperature  was  lower  than  at  present,  and  it  is 
possible  that  the  corresponding  diff'erence  between  the  temperatures  of  the 


378  LAKE  BONNEVILLE. 

adjoiniiig  laud,  then  and  now,  has  not  been  equal  in  amount,  in  which  case 
the  i)ost-Bouneville  warming  of  the  crust  beneath  the  lake  area  has  been 
greater  than  the  coincident  warming  of  the  crust  underlying  contiguous 
areas.  Rise  of  temperature  carries  with  it  expansion,  and  the  hypothesis  is 
that  such  differential  expansion  pniducedthe  observed  differential  altitudes. 
( )ur  (piantitative  data  are  here  less  precise  than  in  the  case  of  the  preceding 
hypothesis,  but  it  is  not  difficult  to  assign  to  them  reasonable  limiting  values, 
so  as  to  obtain  a  practical  test  of  the  hypothesis.  The  mean  annual  tempera- 
ture at  Salt  Lake  City  is  51°  F.,  and  this  may  be  assumed  for  the  entire  basin. 
Its  ancient  climate  was  somewhat  colder,  but  the  moderate  development  of 
glaciers  permits  us  to  entertain  the  assumj)tion  that  the  difference  was  small. 
The  lake,  as  we  know  from  its  wave  wox-k,  was  not  frozen,  and  as  it  had 
great  depth,  we  are  assured  by  the  analogy  of  modern  examples  that  its 
bottom  temperature  was  that  of  water  of  maximum  density,  about  39°.  The 
surface  temperature  of  the  crust  in  the  lacustral  area  was  therefore  12 
degrees  lower  than  now.  If  we  assume  that  the  surface  temperature  of  the 
surrounding  land  was  only  two  degrees  lower  than  now,  we  are  certain  to 
underestimate  the  climatic  change,  and  thus  allow  a  maximum  or  limitinsf 
difference  between  the  crustal  changes  under  the  old  lake  and  under  the 
old  land.  The  problem  then  takes  the  form:  What  uplift  can  be  referred 
to  the  expansion  of  the  upper  portion  of  the  earth's  crust  consequent  on  a 
superficial  rise  of  temperature  of  10  degrees  occurring  at  the  close  of  the 
Bonneville  epoch.  The  remaining  constants  necessary  for  its  solution  are 
obtained  by  assuming  the  coefficient  of  expansion  of  the  rock  involved  to 
])e  0.000006  for  each  degree,  by  adopting  Sir  William  Thomson's  coefficient 
of  dift'usion  of  heat  in  the  earth,  and  by  assigning  to  post-Bonneville  time  a 
duration  of  100,000  years,  an  estimate  intentionally  large.  For  the  com- 
putation of  the  vertical  rise  of  the  basin  from  these  numerical  data  I  am 
indebted  once  more  to  Mr.  Woodward,  who  has  recently  re\'iewed  the  sub- 
ject of  subterranean  temperatures  from  the  mathematical  side.  His  result 
(see  Appendix  C)  is  1.28  feet,  an  amount  quite  too  small  for  om-  considera- 
tion in  this  connection. 


DEFORMATION^  OP  EARTH'S  CRUST.  379 

HYPOTHESIS  OF  TERRESTRIAL  DEFORMATION  BY  LOADING  AND  UNLOADING. 

The  third  hypothesis  exphiius  the  pheiiouieiui  Ijy  assuming  that  when 
the  BonneviHe  Basin  was  tiUed  with  water,  the  earth  yiekled  to  the  weig-ht 
of  the  water,  permitting  a  (h^pressiou  of  the  headed  area,  and  tliat  when  the 
water  was  afterward  remo\'ed,  tliere  was  a  corresponding  rise  of  the  unhjaded 
area.  The  manner  of  yiekhng,  the  amount  of  vertical  change,  and  tlie 
figure  of  deformation  all  depend  on  the  constitution  of  the  earth,  and  as 
that  constitution  is  unknown,  it  is  necessary  to  make  assumptions  regarding 
it  iu  order  to  discuss  the  quantitative  sufficiency  of  the  hypothesis.  If  the 
earth  were  perfectly  rigid,  the  removal  of  the  Bonneville  load  would  not 
affect  its  form;  if  the  earth  were  completely  liquid,  the  removal  of  the  load 
would  cause  the  load  to  be  replaced  by  the  uprising  of  an  equal  weight  of 
matter.  Neither  of  these  extreme  conceptions  can  be  entertained,  for  the 
visible  portion  of  the  eartli  is  neither  liquid  nor  perfectly  rigid,  but  between 
them  is  room  for  an  infinite  variety  of  special  assumptions  under  each  of 
which  some  deformation  of  the  basin  must  be  assigned  to  the  unloading. 

In  order  to  learn  the  order  of  magnitude  of  the  greatest  possible 
deformation,  let  us  assume  for  a  moment  that  the  earth  is  constituted  by  a 
thin  solid  crust  resting  upon  a  liquid  substratum,  and  that  the  rigidity  of 
this  crust  is  very  small  in  comparison  with  the  stresses  applied  to  it  by  the 
removal  of  the  water  from  the  Bonneville  Basin.  The  floor  of  the  basin 
will  then  rise  under  the  action  of  these  stresses  in  some  sort  of  arch, 
whose  interior  will  be  filled  by  liquid  matter  derived  from  surrounding- 
regions.  The  weight  of  tlie  liquid  matter  thus  introduced  will  lie  approxi- 
mately equal  to  the  weight  of  the  water  removed  by  evaporation,  and  the 
height  of  the  crustal  arch  will  be  related  to  the  depth  of  tlie  water  in 
(approximately)  the  inverse  ratio  of  the  densities  of  the  two  liquids.  Tlie 
liquid  rock  may  be  assumed  to  agree  in  density  with  the  average  density 
of  visible  rocks  at  the  surface,  2.75,  and  this  gives  us  as  the  heiglit  of  the 
I'esulting  arch  the  quotient  of  1000  feet  by  2.75,  or  364  feet.  This  is  the 
height  attainable  by  the  arch  on  the  supposition  that  the  strength  of  the 
crust  is  a  vanishing  quantity,  and  it  is  the  superior  limit  of  all  possible 
values  for  the  height  of  the  arch.     With  the  strength  a  vanishing  quantity, 


380  LAKE  BONNEVILLE. 

the  vertical  stresses  due  to  unloading  are  equilibrated  by  vei'tical  stresses 
due  to  gravitation,  and  the  height  of  arch  is  304  ft ;  with  the  strength  finite, 
the  stresses  of  unloading  are  equilibrated  partly  l)y  stresses  of  gravitation 
and  partly  by  elastic  strains,  and  the  height  of  arch  is  a  function  of  tlie 
stresses  of  gravitation.  While  the  natvire  of  this  function  is  more  conq)lcx 
than  that  of  simple  proportion,  it  is  fair  to  infer  from  a  comparison  of  tlic 
observed  height  of  the  arch  of  deformation,  129  ft.,  with  tlie  limiting  heiglit, 
3G4  ft.,  that  under  this  hypothesis  the  stresses  from  unloading  arc;  satisiicd 
chiefly  by  elastic  strains  and  secondarily  by  gravitational  stresses.'  Tluit 
this  implies  great  strength  of  crust  Ijecomes  apparent  when  the  magnitude 
of  the  load  removed  and  the  width  of  the  affected  area  are  considered.  For 
the  sake  of  illustration,  assume  that  129  feet  of  uplift  satisfy  tlie  stres.ses 
due  to  355  feet  (129  X  2.75)  of  the  removed  water;  there  remain  the  stresses 
due  to  645  feet  to  be  satisfied  by  strains  in  the  crust.  Call  the  basin  floor 
a  beam,  120  miles  long,  supported  at  the  ends,  and  sustained  throughout 
by  flotation  so  far  as  its  own  weight  is  concerned.  Call  the  modulus  of 
rupture  of  its  material  3,000  pounds  to  the  stpxare  inch,  and  introduce  no 
fiictor  of  safety.  Consider  the  beam  to  be  suljjected  to  upward  stress  1)}' 
the  removal  of  645  feet  of  water  from  its  entire  upper  surface,  and  compute 
by  the  engineer's  formula  the  depth  of  beam  necessary  to  stand  the  strain. 
It  is  about  32  miles.-  The  illustration  is  a  rude  one,  because  the  floor  of 
the  basin,  being  attached  all  about  its  periphery,  is  stronger  than  a  beam 
supported  only  at  the  ends;  because  a  crust  graduating  into  a  li(piid 
beneath  is  weaker  than  a  homogeneous  crust;    because  the  modulus  of 

•  If  we  postulate  a  tliick  crust  it  is  proper  to  postulate  also  that  the  matter  flowing  In  beneath 
the  dome  has  a  greater  density  than  superficial  rock.  Wilh  the  density  3.5 — an  rxtronie  assumption  — 
tlie  limiting  height  of  arch  is  280  feet. 

-The  engineers'  formula  is 

where  W  is  the  breaking  stress  in  pounds,  the  stress  being  evenly  distributed  over  the  upper  surface 
of  the  beam;  R  Is  the  modulus  of  rupturi'  of  the  material  in  poumls  pir  scinare  inch  ;  b  is  the  lireadlh 
of  the  beam,  (fits  depth  and  I  its  kiigtli.  In  the  case  under  cunsideratlon  W  =D(j/h,  in  which  I)  is  the 
depth,  in  feet,  of  water  removed,  and  (/  is  the  weight,  in  pounds,  of  a  column  of  water  one  inch  scjuaro 
and  one  foot  in  height.  Substituting  this  value  for  W  in  the  formula,  transposing  and  reducing,  wo 
obtain 

2  =  .434  pound.     Making  1  =  120  miles,  D  =  G45  feet  aud  U  =  3000  pounds,  we  find  d  =  M.7  miles. 


UiSTLOADING  AND  UPAEOHING.  381 

viscous  distortion  is  less — possibly  far  less — tlian  the  modulus  of  rupture; 
and  for  other  reasons;  l)ut  it  nevertheless  assists  the  iniaginatiou  in  i-ealiz- 
ing  the  relation  of  bulk  to  strength.  Witli  its  aid  I  trust  tlie  reader  \\  ill 
follow  me  in  tlic  conclusion  that  the  hypothesis  of  local  deformation  of  tlic 
earth  l)y  local  unloading  aifords  results  of  the  same  order  of  magnitude  as 
the  observed  distortion  of  the  plane  of  the  Bonneville  shore,  and  is  quanti- 
tatively adequate. 

The  first  and  second  hypotheses  having  been  foinid  quantitatively  in- 
adequate, the  third  is  the  only  one  meriting  further  discussion.  A  thoi-ongli 
treatment  is  on  the  one  hand  highly  desirable  and  on  the  other  beset 
with  difficulties.  It  is  desirable  because  it  pi'oraises  to  throw  some  light  on 
the  condition  of  the  interior  of  the  earth;  a  solid  earth  would  not  yield  the 
same  deformation  as  an  earth  partly  liquid;  a  highly  rigid  earth  would  be- 
have differently  from  one  of  feebler  rigidity.  It  is  difficult  because  it  must 
deal  with  magnitudes  and  pressures  far  beyond  the  field  of  experimenta- 
tion, and  can  be  accomplished  only  Ijy  the  aid  of  comprehensive  mathe- 
matical analysis.  It  requires  an  analytic  theory  of  the  strains  set  up  by  a 
stress  applied  locally  to  the  surface  of  the  earth  and  of  the  resulting  defor- 
mation, and  this  theory  must  be  so  general  as  to  include  divers  assumptions 
as  to  the  variation  of  elasticity  with  depth  from  the  surface,  and  as  to  the 
relation  of  the  strains  to  the  limits  of  elasticity.'  The  evolution  of  such  a 
theory  is  beyond  my  power,  but  in  the  belief  that  it  is  worthy  of  the  attention 
of  the  mathematician  and  physicist,  I  will  endeavor  to  state  the  problem. 

Assume,  first,  that  the  rigidity  of  the  earth  is  uniform  throughout,  or 
at  least  for  some  hundreds  of  miles  from  the  surface,  its  modulus  of  elas- 
ticity being  that  of  granite,  fi)r  example.  Then  conceive  the  application  to 
the  surface  of  a  lenticulai-  Ixxly  of  water  etpiivalent  to   Lake  Boinic\il]e, 

'As  defined  by  Sir  Williani  Thomson,  "  Elasticity  of  matter  is  that  property  in  virtim  of  wbith  a 
body  requires  force  to  chan};e  its  bulk  or  shape,  and  requires  a  coritiimoiis  apiillciitioii  of  tlio  force  to 
maintain  the  chauj^e,  and  .spriuss  baclc  when  tlic  force  is  removed,  and  if  left  at  rest  without  the  force, 
does  not  remain  at  rest  except  in  its  ))rovions  bulk  and  shape."  Elasticity  of  bnlk  and  elaslicity  of 
shape  are  distinct  properties,  which  coexist  iu  solids,  but  not  in  liqnids.  Kiii;iility  is  synonymous  with 
elasticity  of  shape.  Solids  differ  iu  regard  to  rigidity  in  two  ways.  They  have  dilfcrcnt  moduli  of 
ri^dity  and  differeut  limits  of  rigidity  or  elasticity.  The  niodulns  of  rigidity  depends  upon  the 
.stress  necessary  to  jiroduce  a  unit  of  deformation,  or  upon  the  deformation  produced  by  a  unit  of  stress. 
The  limit  of  rigidity  is  reached  when  the  force  applied  is  so  great  that  after  its  removal  the  solid  does 
not  return  to  its  original  shape. 


382  LAKE  BONNEVILLE. 

but  spnmetric.  To  imagine  the  result,  it  is  necessary  to  divest  the  mind 
of  the  ideas  of  brittleness  and  great  strength  ordinarih-  associated  with 
granite  and  other  massive  rocks.  Brittleness  is  a,  surface  phenomenon 
only;  at  a  depth  of  a  few  thousand  feet,  or  at  most  a  few  miles,  the  tend- 
ency to  fracture  is  effectively  opposed  by  ])ressure.  Strength  is  condi- 
tioned by  magnitude,  and  in  relation  to  magnitude  it  is  a  diininishing  func- 
tion. Structures  of  the  same  form  and  material  are  not  strong  in  pro])or- 
tion  to  their  size  but  are  relatively  weaker  as  they  are  larger  until  hnally 
they  can  not  sustain  their  own  weight.  In  a  general  way  strength  increases 
with  the  square  of  the  linear  dimension;  weight  and  otlicr  luads  increase 
M  itli  tlie  cube.  Giving  due  weight  to  these  considerations,  it  is  not  improper 
to  compare  the  earth  when  loaded  by  the  water  of  Lake  Bonneville  with  a 
bowl  of  jelly  upon  wliich  a  coin  has  been  laid.  The  results  in  either  case 
are,  tirst,  the  depression  of  the  area  beneath  the  load,  second,  the  formation 
of  an  annular  ridge  about  it,  and  third,  the  production  of  strains  within  the 
mass.  Conversely,  the  removal  of  the  water  of  Lake  Bonneville  would  pro- 
duce an  uprising  of  the  central  area  of  the  basin  and  an  annular  depression 
all  about,  and  would  either  relieve  the  strains  previoitsly  produced  by  the 
addition  of  the  water,  or,  if  these  strains  had  been  otherwise  relieved,  would 
set  up  a  new  system  with  opposite  signs.  It  is  easy  to  understand  from  the 
homologous  phenomena  of  jellies  that  the  precise  figure  of  tlie  superficial 
deformation  Avould  de])end  on  the  modulus  of  elasticity  of  the  earth  material. 
With  a  low  elasticity  the  central  arch  would  be  high;  with  a  high  elasticity 
the  figure  of  deformation  would  be  comparatively  low. 

There  are  two  elements  of  complexity  that  inhere  in  the  subject.  In 
the  first  place,  the  deformation  of  the  earth  is  resisted  not  only  l)y  the  elas- 
ticit}'  of  the  material  but  l)v  gravitation,  which  always  tends  to  give  the 
siu'face  the  normal  configuration  of  the  gcoid.  In  the  second  place,  the 
stresses  created  l)v  the  removal  of  the  Homicvillc  water  wnuld  have  certain 
effects  through  the  property  of  bulk  elasticitv  as  well  as  that  of  shape  elas- 
ticity. It  is  not  improbaljle  that  a  suitable  discussion  of  tlie  subject  would 
demonstrate  that  the  deformations  ascribable  to  ])ulk  elasticity  are  too  small 
for  consideration  in  connection  with  those  referable  to  shape  elasticity,  l)ut 
to  this  extent  at  least  thev  Avould  need  to  be  considered. 


UNLOADING  AND  U PARCHING.  383 

Add  now  a  third  element  of  complexity,  by  assuming  tliat  tlie  strains 
set  lip  by  the  removal  of  the  water  are  not  entirely  within  the  limit  of  elas- 
ticity of  the  material.  Wherever  they  exceed  the  elastic  limit,  change  of 
another  sort  occurs,  probably  not  fracture,  as  in  laboratory  experiments  on 
the  limits  of  elasticity,  but  flow — such  flow  as  Tresca's  experiments  have 
demonstrated  for  colloids.^  The  plastic  yielding  of  the  rock  in  the  region 
of  greatest  strains  woidd  cause  a  partial  redistribution  of  strains  in  adja- 
cent regions,  and  would  correspondingly  modity  the  figure  of  deformation. 
The  height  of  the  central  arch  would  be  increased. 

Now  add  yet  one  other  element  of  complexity,  by  assuming  that  the 
modulus  of  shape  elasticity  and  the  limit  of  shape  elasticity  vary  (simulta- 
neously and  harmoniously)  in  accordance  with  some  law  involving  the  dis- 
tance from  the  surface.  They  niay  increase  from  the  surface  down^^^ard, 
or  they  may  decrease  from  the  surface  downward,  and  in  the  latter  case 
liquidity  will  at  some  depth  be  reached.  The  actual  deformation  should  be 
comparatively  low  if  the  elasticity  increases  downward,  and  comparatively 
high  if  the  elasticity  diminishes  downward. 

The  application  of  an  analytic  theory  of  these  relations  could  yield  the 
best  results  only  with  a  better  determination  than  we  now  have  of  the  elastici- 
ties of  rocks,  and  with  a  better  determination  of  the  figure  of  the  deforma- 
tion of  the  Bonneville  Basin;  but  even  with  the  imperfect  data  at  liand  it 
might  establish  a  presumption  for  or  against  the  existence  of  a  liquid  sub- 
stratvim  beneath  the  rigid  crust,  and  if  the  mathematical  difficulties  were 
surmounted,  there  can  be  little  question  that  the  observational  data  would 
be  supplied,  for  their  procurement  is  opposed  by  little  beside  their  expense. 

Without  waiting  for  the  mathematician,  we  may  conclude  in  a  general 
way  that  the  floor  of  the  Bonneville  area  arched  upward  when  the  load  of 
water  was  removed,  and  that  this  deformation  was  permitted  by  the  feeble 
elasticity  or  the  imperfect  elasticity,  or  l)oth,  of  the  portion  of  the  earth 
affected;  the  conclusion  being  qualified  l)y  whatever  weakness  inheres  in 
the  postulate  that  the  coincidence  in  time  and  place  of  crust  unloading  and 
crust  deformation  is  not  fortuitous 

>M6m  de  I'Inst.  Savants  strangers,  vol.  18,  186S. 


384  LAKE  BONNEVILLE. 

EVIDENCE  FROM  THE  POSITION  OF  GREAT  SALT  LAKE. 

In  an  earlier  chapter  attention  has  been  called  to  the  fact  that  in  the 
central  portion  of  the  basin  of  the  main  body  of  Lake  Bonneville  mountain 
ridges  are  so  nearly  buried  by  lacustrine  sediments  that  only  their  summits 
remain  visible,  jutting  forth  from  the  plain  after  the  manner  of  islands. 
The  amount  of  sedimentation  implied  is  great,  and  its  magnitude  is  like- 
wise indicated  by  the  general  evenness  of  the  plain.  Wherever  the  writer 
has  crossed  a  portion  of  this  plain,  he  has  found  himself,  after  leaving  the 
foot  slope  of  the  contiguous  mountains,  upon  a  plnya  Hoor  with  no  discern- 
ible inclination,  and  nearly  bare  of  vegetation.  The  saltness  of  tlie  soil 
testifies  that  water  does  not  flow  across  it,  but  rather  stands  upon  it  and 
evaporates.  Another  evidence  of  the  general  evenness  of  surface  is  the 
shallowness  of  Great  Salt  Lake,  which  has  a  mean  depth  of  less  than  IT) 
feet. 

At  the  present  time  the  principal  contrilnition  of  debris  toward  the  iill- 
ino-  of  the  basin  comes  from  the  east.  On  the  coast  of  Great  Salt  Lake 
deltas  have  been  observed  only  at  the  mouths  of  the  Jordan,  the  Weber, 
and  the  Bear,  all  rising  in  the  Wasatch  and  Uinta  Mountains  and  entering 
the  lake  on  the  eastern  side.  The  western  coast  shows  capes  only  where 
rocky  hills  stand  near,  and  bays  are  found  where  it  receives  the  intermit- 
tent drainage  of  the  surrounding  valleys.  In  Bonneville  times  the  same 
contrast  existed.  The  deltas  of  the  old  lake  are  found  almost  exclusively 
where  it  received  streanis  from  the  east,  namely,  the  rivers  just  mentioned, 
their  principal  tributaries,  which  then  entered  the  lake  directly,  and  the 
Sevier  River.  No  delta  terraces  were  observed  about  the  nortliern,  west- 
ern, and  southern  margins,  unless  possibly  in  the  Escalante  Desert. 

If  this  deposition,  so  great  in  amount,  iind  dcrivccl  so  largely  from  tlie 
east,  were  the  only  factor  concerned  in  the  dctcnniHatioii  of  the  configura- 
tion of  tlie  desert  floor,  that  floor  would  be  a  gently-sloping  jjlain,  with  its 
higher  margin  at  the  east  and  its  lower  at  the  west,  and  Great  Salt  Lake 
would  lie  at  tlu^  base  of  the  Gosiute  Mountains  instead  of  the  Wasatch. 
The  easterly  position  of  the  lake  is  unquestionnbly  due  to  crustal  move- 
ment, either  orogenic  or  epeirogenic.     (See  PI.  XLVIl.) 


ECCENTRICITY  OF  GREAT  SALT  LAKE.  385 

Let  us  first  consider  tlie  possibility  of  an  erogenic  cause.  The  most 
conspicuous  recent  orogenic  change  in  the  region  is  that  shown  by  the  fault 
scarps  at  the  base  of  the  Wasatch  Range.  These  scarps  show  differential 
movement,  either  ascent  of  the  mountain  or  descent  of  the  valley,  or  both. 
The  great  size  of  the  mountain  range,  as  argued  on  an  earlier  page,  assures 
us  that  a  rising  of  the  range  is  at  least  a  part  of  the  displacement,  but  is 
not  opposed  to  the  idea  that  the  sinking  of  the  valley  is  a  correlative  and 
perhaps  equal  part.  It  is  consistent  with  this  idea  that  the  water  of  Great 
Salt  Lake  between  the  Bear  and  Weber  deltas,  and  again  between  the 
Weber  and  Jordan  deltas,  approaches  within  about  a  mile  of  tlie  great 
fault  at  the  mountain  base. 

Epeirogenic  causes  may  be  considered  from  two  points  of  view:  first, 
as  belonging  to  a  system  of  changes  correlated  with  the  emptying  of  the 
basin  by  evaporation;  second,  as  belonging  to  the  more  general  system  of 
changes  to  which  the  basin,  as  such,  may  be  ascribed.  Taking  the  first 
point  of  view,  we  have  a  post-Bonneville  rising  of  the  central  area  amount- 
ing to  more  than  100  feet,  and  it  is  conceivable  that  this  has  divided  the 
plain  into  two  basins,  of  which  the  lake  occupies  one,  while  the  other  con- 
tains only  occasional  playa  lakes,  such  as  the  scant  rainfall  of  the  tributary 
regions  is  able  to  produce.  Too  little  is  known  of  the  configuration  of  the 
desert  west  of  the  lake  to  determine  whether  it  is  partitioned  off  by  a  bar- 
rier of  such  sort,  or  is  in  time  of  great  rainfall  tributary  to  Great  Salt  Lake. 
But  there  are  other  reasons  why  the  hypothesis  can  not  be  seriously  enter- 
tained. In  the  first  place,  the  area  of  maximum  uplift,  so  far  as  our  meas- 
urements determine  it,  coincides  with  the  western  portion  of  the  lake 
instead  of  with  the  line  of  low  ridges  beyond  it.  The  old  shore-line  is 
higher  on  Promontory  Ridge  than  on  the  Terrace  Mountains  to  the  west- 
ward. 

It  must  also  be  borne  in  mind  that  the  present  condition  of  the  Ijasin 
as  affected  by  climate  is  substantially  identical  with  the  [)re-Bonneville 
condition,  and  the  arid  phase  was  of  long  continuance  before  the  Bonne- 
ville flood.  Whatever  central  elevation  is  recorded  by  the  surviving  shore- 
line is  merely  the  correlative  of  central  depression  during  the  lake  period, 

and  to  assume  the  post-Bonneville  uplifting  of  the  plain  into  a  barrier  ade- 
MON  I 25 


386  LAKE  BONNEVILLE. 

(piate  to  contain  the  lake  is  to  assume  that  during  the  existence  of  tlie  lake 
the  central  depression  was  filled  by  sediments  so  as  to  pi-oduce  a  lake  bot- 
tom almost  absolutely  level.  From  wliat  we  know  by  observation  of  the 
slopes  on  which  the  Bonne\'ille  sediments  were  able  to  lie,  we  can  not 
believe  that  this  was  accomplished,  but  rather  that  throughout  the  deeper 
portion  of  the  lake  there  was  an  equable  deposition  over  gentle  slopes,  the 
depth  of  deposit  increasing  rather  toward  the  source  of  the  material  at  the 
east  than  toward  the  center  of  the  lake.  It  is  pn)l)iible  that  post-Bouneville 
changes  in  the  configuration  of  the  plain,  so  far  as  they  have  depended  epei- 
rogenically  on  the  removal  of  the  water,  have  been  the  simple  converse  of 
changes  due  to  the  previous  imposition  of  the  water,  and  have  practically 
restored  the  preexisting  condition. 

Turning  to  epeirogenic  considerations  of  a  more  general  nature,  we 
see  that  the  Bonneville  Basin  is  a  region  of  depression,  surrounded  on  the 
south,  west  and  north  by  regions  of  somewhat  greater  elevation,  and  on  the 
east  by  a  tract  whose  mean  altitude  is  several  thousand  feet  higher— an 
irregular  plateau,  along  the  edge  of  whit-h  the  Wasatch  Range  stands  as  a 
parapet.  The  forces  which  produced  this  bashi  and  the  plateau  to  tlie  east 
of  it  are  of  necessity  independent  of  the  loading  and  unloading  of  the  basin, 
and  of  a  more  general  nature.  Whatever  they  may  be,  it  is  not  irrational 
to  appeal  to  them  as  the  cause  of  the  local  depression  containing  Great  Salt 
Lake  and  to  regard  that  depression  as  a  result  of  the  mere  continuance, 
with  possibly  greater  localization,  of  the  process  which  created  the  larger 
basin. 

Whether,  then,  we  regard  the  peculiar  position  of  the  lake  as  a  result 
of  orogenic  or  of  epeirogenic  dis])lacement,  we  are  comijelled  to  forego  tlie 
assignment,  even  tentatively,  of  a  special  hypotliesis  as  to  its  causr.  I*ci'- 
haps  tlie  most  valuable  cont'lusiou  to  be  drawn  is  tliat,  as  drposition  witliiii 
tlie  liasin,  during  Imiiiid  and  arid  phases  of  climate  alike,  lias  (•(Hitiiiiially 
tended  to  build  the  eastern  lialf  of  the  plain  liiglicr  tliaii  the  western,  and. 
as  this  tendency  has  continued  to  the  present  time,  the  sul)sidence  opposing 
and  thwarting  it  has  likewise  continued  to  a  late  epoch  and  is  probably  still 
in  progress. 


COROLLARY.  387 

THE  STRENGTH  OF  THE  EARTH. 

The  writer  has  been  led  by  the  discussion  of  these  phenomena  to  a 
conception  of  the  rigidity  or  strength  of  the  earth,  more  definite  than  he 
had  previously  entertained.  It  would  not  be  proper  to  call  this  conception 
a  conclusion  from  the  data  here  presented,  or  a  result  to  which  they  rigor- 
ously and  necessarily  lead.  It  is  rather  a  working  hypothesis  suggested 
by  the  study  of  Lake  Bonneville. 

If  the  earth  possessed  no  rigidity,  its  materials  would  arrange  them- 
selves in  accordance  with  the  laws  of  hydrostatic  equilibrium.  The  matter 
specifically  heaviest  would  assume  the  lowest  position,  and  there  would  be 
a  gradation  upward  to  the  matter  specifically  lightest,  which  would  consti- 
tute the  entire  surface.  The  surface  would  be  regularly  ellipsoidal,  and 
would  be  completely  covered  by  the  ocean.  Elevations  and  depressions, 
mountains  and  valleys,  continents  and  ocean  basins,  are  rendered  possible 
by  the  property  of  rigidity,  but  the  phenomena  of  diastrophism,  and  espe- 
cially those  of  plication,  show  that  this  rigidity  has  its  limits,  and  the 
phenomena  of  volcanism  demonsti-ate  that  its  distribution  is  not  uniform. 
It  has  been  computed  by  Darwin'  that  if  the  earth  were  homogeneous 
throughout,  the  stress  differences  occasioned  by  the  weight  of  continents 
would  be  as  great  as  those  necessary  to  crush  granite.  The  stress  differ- 
ence necessary  to  produce  viscous  flow  in  granite  and  allied  rocks  is  not 
known,  but  if  different  from  the  crushing  stress,  it  is  less;  and  Darwin's 
discussion  therefore  tends  to  show  that  the  earth,  if  homogeneous,  would 
require  a  strength  equal  to  or  greater  than  that  of  granite.  Tliat  the  earth 
is  not  homogeneous  as  regards  density  (and  does  not  consist  of  symmetric 
homogeneous  shells)  is  shown  l)y  the  massing  of  land  ;ireas  in  one  hemis- 
phere; and  the  hypothesis  that  the  crust  has  low  density  beneath  continents 
and  high  density  beneath  oceans  is  sustained  by  observations  on  the  local 
direction  and  local  force  of  gravitation  at  various  points.-  The  general 
proposition,  tacitly  postulated  by  Babbage  and  Herschel,  advocated  more 

'  On  the  stresses  caused  in  the  interior  of  the  earth  hy  the  weight  of  continents  and  nioiiutains, 
by  G.  H.  Darwin.     Phil.  Trans.  Royal  Soc,  pt.  1,  1882. 

2  On  the  argument  from  geodetic  station  errors  see  John  H.  Pratt,  Figure  of  the  Earth,  p.  201. 

On  the  argument  from  pendulum  observations  see  H.  Faye  iu  Revue  scientifniue  for  Feb-  20  and 
March  27,  188G. 


388  LAKE  ];ONNEVILLK. 

recently  by  Dutton  and  Fisher,  and  entertained  ])y  most  modem  writers, 
is  that  the  radial  elements  of  the  sphere  have  the  same  weight  on  all  sides, 
the  product  of  the  height  of  each  unit  colunui  into  its  mean  density  being 
everywhere  the  same.  With  such  a  distribution  of  densities  the  stresses 
and  strains  resulting  from  the  existence  of  continental  elevations  do  not 
disappear,  but  they  are  less  than  those  derived  by  Darwin  on  th^  hyi)oth- 
sis  of  homogeneity.  How  much  less  has  not  been  shoAvn,  but  it  is  fair  to 
say  that,  so  far  as  the  evidence  from  continents  is  concerned,  the  (juestion 
of  the  degree  of  rigidity  of  the  earth's  nucleus  is  still  an  open  one. 

If  a  weight  l)e  added  to  a  limited  portion  of  the  surface  of  the  globe, 
there  will  result  a  system  of  strains  beneath  and  aljout  the  area,  and  a 
defonnation  of  the  surface  accordant  witli  the  system  of  strains.  If  the 
weight  is  small,  and  if  the  effect  is  not  complicated  by  preexistent  strains, 
the  resulting  strains  will  at  every  point  fall  within  the  limit  of  elasticity  of 
the  material,  and  the  deformation  will  be  small.  If  the  weight  is  sufficiently 
large,  the  resulting  strains  will  in  some  places  exceed  the  limit  of  elasticity, 
and  other  consequences  will  follow.  Among  these,  rupture  and  faulting 
may  in  special  cases  be  included,  but  the  ordinary  and  predominant  res\dt 
will  be  viscous  flow.  The  viscous  flow  will  consume  time,  and  when  it  lias 
ceased,  there  Avill  remain  a  system  of  elastic  strains.  Beyond  the  elastic 
limits,  the  laws  of  change  for  loading  the  surface  of  the  earth  (and  similarly 
for  unloading)  are  quasi-hydi'ostatic. 

The  point  on  which  the  Bonneville  jdienomena  appear  to  throw  light 
is  the  magnitude  of  the  load  necessary  to  overpower  rigidit}-.  The  })lie- 
nomena  of  faulting  at  the  base  of  the  Wasatch,  whether  considered  liy 
themselves  or  in  connection  with  the  filling  of  the  adjacent  valley  ^^  itli 
water  and  its  subsequent  emptying,  appear  to  my  mind  best  accordiint  with 
the  idea  that  the  Wasatch  Range  and  the  paralh'l  ranges  lying  west  of  it  are 
not  sustained  at  their  existing  heights  above  the  adjacent  plains  and  valleys 
by  reason  of  the  inferior  specific  density  of  their  masses  and  of  the  under- 
lying portions  of  the  crust,  but  chiefly  and  perhaps  entirely  in  virtue  of  the 
rigidity  or  strength  of  the  crust.  The  phenomena  of  deformntion  of  the 
Boimeville  shore-line  accord  best  with  the  idea  that  the  imi)osition  of  the 
Bjnneville  load  of  water  and  its  subsequent  i-emoval  strained  the  subjacent 


MEASURE  OF  RIGIDITY.  389 

portions  of  the  crust  beyond  the  elastic  limit,  the  stresses  due  to  tlie  load- 
ing- and  unloading-  being-  partly  equilibrated  by  crustal  strains,  and  partly 
relieved  by  crustal  flow  and  a  resulting  redistribution  of  the  stresses  due  to 
gravitation.  It  is  indicated  that  the  limit  of  terrestrial  rigidity  falls  some- 
where  between  that  measured  by  the  weight  of  the  Wasatch  Range  and 
that  measured  by  the  weight  of  the  water  of  the  main  body  of  Lake  Bon- 
neville, or  in  more  general  terms,  that  a  mountain  of  the  tirst  class  is  the 
greatest  load  that  can  be  held  up  by  the  earth,  and  is  therefore  an  expression 
of  its  strength  or  of  the  limit  of  elasticity  of  the  material  of  its  outer  layers. 

Fully  to  realize  the  nature  of  this  measure,  it  is  necessary  to  give  it 
numerical  expression,  and  to  this  end  a  few  computations  have  been  made. 

It  is  evident  that  the  maximum  strain  produced  by  a  load  depends  in 
part  on  its  distribution,  and  especially  that  a  long  ridge  taxes  rigidity  less 
than  a  compact  mountain  mass  of  the  same  weight.  It  appears  to  me  that 
a  very  long  range  causes  no  greater  strains  than  a  shorter  one  having  the 
same  cross  section,  and  I  have  therefore  conceived  the  Wasatch  Range  to  be 
fairly  represented  for  this  purpose  by  a  division  of  it  including  the  highest 
peaks  and  having  a  length  not  quite  double  its  width.  This  di\ision 
extends  from  the  Provo  River  northward  to  the  low  pass  at  the  head  of 
Parley's  Canyon.     Its  estimated  volume  is  200  cubic  miles. 

Similar  considerations  lead  me  to  base  the  estimate  for  Lake  Bonne- 
ville on  the  main  body  instead  of  the  entire  lake,  excluding  not  only  the 
Sevier  body  but  Snake  Valley,  Wliite  Valley,  and  Utah  Valley  bays. 
Thus  defined,  the  load  of  water  amounted  to  about  2000  cubic  miles,  equiv- 
alent in  weight  to  730  cubic  miles  of  rock.  On  the  assumption  that  the 
strains  produced  by  the  lifting  of  this  load  were  only  in  minor  part  relieved 
by  viscous  flow,  it  is  inferred  that  the  limit  to  tlie  superficial  rigidity  of  the 
earth  is  expressed  by  a  load  of  400  to  600  cubic  miles  of  rock  (1670  to 
2500  cubic  kilometers). 

There  are  four  classes  of  topographic  features  with  which  tliis  measure 
may  advantageously  be  compared,  and  by  which  it  may  perlia])s  be  tested. 
The  first  is  mountains  of  addition,  or  mountains  produced  by  the  mere  addi- 
tion of  matter  to  the  surface  of  the  earth.  IMost  volcanic  cones  are  of  this 
class.     The  second  class  consists  of  mountains  by  subtraction,  or  residuary 


390  LAKE  BONNEVILLE. 

mountains  clue  to  the  removal  of  surrounding  material.  The  third  class  is 
intermediate,  including  addition  and  subtraction,  as  when  the  extrusion  or 
intrusion  of  volcanic  matter  produces  a  resistant  mass  cnpable  of  preserving 
against  erosion  a  residuary  mountain.  The  fourth  consists  of  valleys  by 
subtraction,  or  valleys  eroded  fi'om  plateaus.  Mountains  and  valleys  due 
directly  to  diastropliism  are  not  in  point,  because,  as  they  an;  the  super- 
ficial expression  of  indviiown  subterranean  changes,  we  can  nut  be  sure  in 
individual  cases  that  their  existence  is  independent  of  the  sul)tcrr;inean  dis- 
tribution of  densities.  For  similar  reason,  a  volcanic  inoinit.iin  whose 
building  has  been  accompanied  by  subsidence  of  tlu^  subjacent  tcrrane  can 
not  be  used  for  comparison. 

The  contour  maps  ])repared  by  the  geogi-a])hic  branch  of  the  Survey 
enable  me  to  give  the  volumes  of  some  of  the  most  imjxtrtant  American 
examples  of  these  various  classes  with  a  degree  of  precision  (piite  sufficient 
for  the  purpose.  By  their  aid  each  of  the  following'  features  was  referred, 
not  to  sea  level,  but  to  the  plane  of  the  surrounding  country,  and  its  vol- 
ume was  computed. 

San  Francisco  Mountain  is  a  volcanic  cone  standing  alone  on  a  high 
plain,  and  tlie  strata  about  its  base  are  almost  undisturbed ;  it  is  a  typical 
mountain  by  addition.     Its  volume  is  40  cul^ic  miles. 

Mount  Shasta  is  a  volcanic  cone  standing  in  a  region  of  disturbed 
strata,  but  there  is  no  evidence  of  subsidence  due  to  its  load.  Its  volume 
is  SO  cubic  miles. 

Mount  Taylor  is  a  volcanic  cone  standing  on  a  plain  tioored  with  hard 
lavas.  The  degradation  of  the  surrounding  country  has  converted  the  mA- 
canic  plain' into  a  great  mesa  or  table  mountain.  The  cone  and  mesa 
together,  constituting  a  mountain  by  combined  addition  and  subtraction, 
have  a  vol  nine  of  190  cubic  miles. 

Tlie  Henry  Mountains  and  the  Sierra  La  Sal  consist  each  of  a  grou]) 
of  laccolites — volcanic  additions  by  intrusion — and  of  other  rocks  preserved 
bv  them  from  the  erosive  reduction  sustained  bv  the  sin-rounding  ])lateau. 
Their  vohimes  are  respectively  230  and  250  cubic  miles. 

The  Tavapiits  plateaii  of  the  Green  River  basin,  otherwise  Ivnown  as 
Roan  Mountain,  is  a  great  mass  of  inclined  strata  carved  out  by  the  unequal 


U  S. GEOLOGICAL    SURVEY 


U^J-'Jl    B^'I'II'TE-.TLLE      FL.  LI 


Juhut:.  Bien  it  <;•:■   Lith 


..,  U    I  H  }:vi.sl..i 


SKETCH  MAP    OF 

BLACK  ROCK  AND  VICINITY,  UTAH 

PREPARED  TO    SHOW  THE  POSITION  OF 
THE  GRANITE  POST  KNOWN  AS  THE 

BLACK  ROCK  BENCH. 


Surveyed  in  1877, by  G.K.GilbeiL  . 


MOUNTAIN  VOLUMES.  391 

degradation  of  a  still  greater  anticlinal.  Its  determining  cause  is  a  thick 
layer  of  resistant  rock  lying  between  thick  layers  of  yielding  rock,  and  it 
stands  between  two  nionoclinal  valleys  due  to  the  excavation  of  the  yielding 
layers.  Its  volume  standing  above  the  level  of  the  adjacent  valleys  is  about 
700  cubic  miles. 

The  Grand  Canyon  of  the  Colorado  is  a  valley  cut  from  a  great  })lateau 
of  stratified  rock.  The  plateau  has  a  fault  structure  of  its  own,  but  the 
canyon  and  the  fault  structure  have  different  directions  and  are  manifestly 
independent.  The  volume  excavated  to  form  the  deeper  part  of  tlie  canyon, 
from  the  mouth  of  the  Little  Colorado  to  the  mouth  o(  Kanab  Creek,  is  350 
cubic  miles. 

The  Appalachian  Mountains  are  traversed  for  nearly  a  thousand  miles 
l)y  a  great  valley  following  the  outcrop  of  yielding  rocks,  and  it  is  probaV)le 
that  we  have  here  a  valley  by  subtraction.  For  the  same  reason  that 
determined  the  selection  for  measurement  of  a  portion  only  of  the  Wasatch 
Range  and  of  a  portion  only  of  Lake  Bonneville,  measurement  was  not 
made  of  the  whole  of  this  valley,  but  only  of  a  limited  part.  It  was  assumed 
that  a  section  with  length  fifty  per  cent,  greater  than  breadth,  and  selected 
where  tlie  valley  is  broadest,  fairly  represents  the  strain-producing  power 
of  the  whole  valley.  The  portion  thus  selected  lies  600  feet  below  the  mean 
height  of  the  Cumberland  Plateau  on  the  northwest  and  1000  feet  below 
the  mean  height  of  the  mountain  district  of  North  Carolina  on  the  southeast, 
and  its  volume,  computed  from  the  mean  of  these,  is  800  cvubic  miles. 

All  of  these  various  features  except  two  fall  within  the  indicated  limit 
of  GOO  cubic  miles,  but  the  limit  is  exceeded  by  the  Tavaputs  Plateau  with 
700  and  the  Appalachian  valley  with  800  cubic  miles.  There  are  qualify- 
ing considerations  in  each  case.  The  plane  above  which  the  volume  of  the 
Tavaputs  Plateau  was  computed  was  that  of  the  low  valleys  adjoining  it; 
|)erhaps  a  more  suitable  plane  of  reference  would  have  been  the  general 
level  of  the  surrounding  country.  The  density  of  the  rock  of  the  plateau 
is  probably  less  than  2.75,  the  density  assumed  in  reducing  the  volume  of 
the  abstracted  lake  water  to  equivalent  rock  volume.  The  Appalachian 
valley  lies  in  a  region  of  great  corrugation,  and  its  trend  coincides  with  the 
strike  of  the  orogenic  structure.     That  structure  unquestionably  involves 


392  LAKE  BONNEVILLE. 

inequalities  in  the  distribution  of  subteiTanean  densities,  and  it  is  possible 
that  the  strains  due  to  the  valley  are  lessened  by  the  presence  beneath  it  of 
exceptionally  heavy  matter.  But  after  giving  due  weight  to  these  considera- 
tions, it  must  still  be  admitted  that  the  measure  of  strength  does  not  stand 
well  the  test  applied.  It  is  indeed  possible  that  a  true  measure  has  Ijeen 
found,  and  that  it  is  illustrated  by  the  Bonneville,  Tavaputs,  and  Ai)palachian 
phenomena,  but  we  can  not  deny  the  equal  possibility,  first,  that  the  strength 
of  the  earth  varies  so  widely,  in  different  places  that  a  measure  discovered 
in  the  Bonneville  basin  serves  merely  to  indicate  the  order  of  magnitude  of 
a  measure  of  the  average  strength,  or  second,  that  the  unloading  of  the 
Bonneville  basin  occasioned  no  greater  strains  than  the  crust  was  able  to 
endure,  and  that  the  coincidence  of  unloading  and  uparching  was  a  coin- 
cidence merely. 


CHAPTER    IX. 
THE  AGE  OF  THE  EQUUS  FAUNA. 

THE  FAUNA  AND  ITS  PHYSICAL  RELATIONS. 

As  the  Equus  fauna  is  not  known  to  occur  in  the  Bonneville  Basin,  the 
presence  of  this  chapter  requires  explanation.  In  considering  the  relation 
of  the  Bonneville  history  to  glacial  history,  it  has  been  found  necessary  to 
consider  also  the  glacial  and  lacustrine  records  of  the  Mono  and  Lahontan 
Basins;  hence  the  sixth  chapter  contains  an  exceptionally  full  discussion  of 
the  relation  of  the  later  lacustrine  history  of  the  Great  Basin  to  general 
geologic  chronology.  The  Equus  fauna  is  so  connected  with  that  lacustrine 
history  that  the  geologist  can  best  discuss  its  age  in  that  connection.  The 
present  chapter  is  a  corollary  to  Chapter  VI. 

The  same  explanation  serves  to  account  for  the  discussion  of  the  fauna 
by  the  present  writer,  who  has  not  visited  the  chief  localities  of  its  occur- 
rence, but  derives  his  knowledge  of  its  geologic  relations  from  the  writings' 
and  notes  of  Russell  and  McGee. 

Equus  appears  to  have  been  first  used  in  the  nomenclature  of  geologic 
history  by  Marsh,  in  an  address  read  to  the  American  Association  for  the 
Advancement  of  Science  in  1877."  The  Equus  beds  are  there  made  an 
upper  division  of  the  Pliocene,  and  they  are  characterized  in  a  table  accom- 
panying the  address  by  the  genera  Equus,  Tapirus,  and  Elephas.  An  exam- 
ination of  the  text  shows  that  none  of  these  genera  are  credited  to  the  lower 
Pliocene,  but  that  all  are  credited  to  the  post-Tertiary.  The  characteriza- 
tion thus  fails  to  separate  the  Equus  fauna  from  the  Pleistocene,  and  as  no 

'Fourth  Ann.  Kept.  U.  S.  Geol.  Survey,  pp.  4r)8-461.     Science,  vol.  3,  1884,  pp.  322-323. 
-The  Introduction  and  Succession  of  Vertebrate  Life  in  America.     By  O.  C.  Marsh.     Proc.  A.  A. 
A.  S.,  vol.  26,  1878,  p.  211. 

393 


394  LAKE  BONNEVILLE. 

locality  is  mentioned,  it  leaves  the  fauna  undefined.  Two  years  later  the 
fauna  was  charactei'ized  hy  Cope  by  the  following  list  of  mammalian  spe- 
cies.^ Those  of  the  left  hand  column  are  extinct,  those  of  the  ridit  hiiiid 
column  living. 

Mylodon  sodalis.  Tliomomys  near  vlushis. 

Lutra  uenT  pincinaria.  Thomomys  talpoides. 

ElephiDi  primifjeuhis.  Caslor  filirr. 

Equus  occidentaUs.  Canis  lalruns. 

Equus  major. 
Anchcnia  henierna. 
Avchenia  magna. 
Anchenia  vitakeriana. 
Cerims  fortis. 

As  the  species  of  this  list  Avere  found  together  at  one  horizon  and  in 
the  same  locality,  they  afford  a  definite  and  tangible  basis  for  discussion, 
and  I  shall  consider  them  as  the  Equus  fauna,  despite  the  fact  that  they  fail 
to  include  the  genus  Tapirus  referred  to  it  by  Marsh.  The  locality  was  de- 
scribed by  Cope  as  lying  thirty  or  forty  miles  east  of  Silver  Lake,  Oregon,^ 
and  he  styled  it  "Fossil  Lake."  Russell,  who  visited  the  place  in  1882, 
speaks  of  it  as  a  few  miles  eastward  of  Christmas  Lake. 

The  formation  in  which  the  bones  occur  is  lacustrine,  as  shown  by  its 
shells.  It  constitutes  the  floor  of  a  desert  valley,  and  has  suffered  scarcely 
any  erosion,  though  the  sand  dunes  traveling  over  it  suggest  that  its  surface 
may  have  been  somewhat  degraded  by  wind  action.  All  about  the  sides 
of  the  valley  are  shore-lines,  and  above  these  shore-lines  the  lake  beds  are 
not  found.  Just  as  in  the  Bonneville  and  Lahontan  basins,  the  physical 
relations  indicate  that  the  shore-lines  and  lacustrine  sediments  are  coordi- 
nate products  of  the  same  expansion  of  lake  waters. 

The  Christmas  Lake  basin  is  part  of  the  Great  Basin,  and  lies  L50 
miles  northwest  from  the  Lahontan  shore-lines.  Each  closed  vallev  of  the 
intervening  region  has  its  ancient  shore-line  and  associated  lake  beds.  Each 
of  the  old  lakes  thus  demonstrated  stands  witness  to  climatic  oscillation, 
and  their  geograi)hic  relations  leave  no  room  for  question  that  they  jjertain 
to  the  same  climatic  oscillation  and  therefore  have  the  same  date. 


'E.  U.  Cope:  Bull.  U.  S.  Geol.  &  Geofr.  Survey  of  tlio  Territories,  vol.  5,  1879,  p.  48. 
'Americau  Naturalist,  vol.  16,  18e2,  p.  194. 


CORRELATION  OF  EQUUS  AND  LAHONTAN  FAUNAS.  395 

The  mammalian  remains  obtained  from  the  Lahontan  l)c(ls  inckide  a 
great  proboscidian  (^Elephas  or  Mastodon),  a  llama,  one  or  more  horses,  and 
an  ox.  No  skeletons  were  found,  and  the  dissociated  bones  and  fragments 
of  bones  are  not  such  as  to  permit  the  recognition  of  species;  but  Prof. 
Marsh,  to  whom  they  were  submitted,  was  able  to  say  with  entire  confi- 
dence that  the  specimens  as  a  whole  belong  to  the  Equus  fauna.  Having 
myself  compared  the  Lahontan  collection  with  the  collection  made  by  Mr. 
Russell  at  the  Christmas  Lake  locality,  I  may  be  permitted  to  add  that  I 
share  Prof.  Marsh's  confidence  in  the  identity  of  the  faunas. 

The  correlation  receives  additional  support  from  the  lacustrine  shells. 
Russell  repoi'ts  from  the  l)one  beds  near  Christmas  Lake  the  following 
species:' 

Sphwriiim  dcntatum.  Limnopln/fta  hiilimoides. 

PifiuliHin  nltrnmontanum.  Garinifex  newhcrryi. 

Helisoma  trirolvis.  Valvatn  rireiis. 
Gyraiihis  rermicularis. 

None  of  these  are  extinct,  and  all  have  been  found  in  Lahontan  strata. 

Nearly  all  of  the  bones  obtained  from  the  Lahonton  strata  were  found 
at  a  horizon  somewhat  above  the  middle  of  the  upper  division  of  lake 
beds.  At  "Fossil  Lake"  the  bones  were  found  at  the  top  of  the  formation, 
but  we  know  nothino-  of  the  thickness  of  the  formation.  Unless  the  Fossil 
Lake  formation  is  much  thinner  than  the  Lahonton,  the  date  of  its  discov- 
ered mammalian  fjiuna  is  a  trifle  later. 

The  physical  relations  recited  above,  and  the  associated  paleontologic 
relations,  show  that  the  Equus  fauna,  as  illustrated  by  its  type  locality, 
belongs  to  the  epoch  of  the  Upper  Lahontan.  It  therefore  falls,  as  a  mat- 
ter of  general  chronology,  in  the  later  Pleistpcene. 

This  conclusion  ditfers  widely  from  that  reached  by  purely  paleonto- 
logic methods,  for  these  refer  the  fauna  to  the  later  Pliocene.  Before  they 
are  considered,  attention  will  be  called  to  a  possible  ambiguity,  and  one  of 
the  lines  of  physical  evidence  will  be  amplified. 

The  term  Pleistocene  is  used  by  geologists  in  two  senses,  one  of  which 
may  be  characterized  as  chronologic  or  general  and  the  other  as  physical 

'  Fourth  Ann.  Eept.  U.  S.  Gcol.  Snrv.,  p.  460. 


396  LAKE  BONNEVILLE. 

or  local.  In  Europe  the  later  part  of  Cenozoic  time  was  tUstingtiislied  1)\- 
a  series  of  physical  events  including  one  or  more  epochs  of  exce})ti()nal 
cold  and  exceptional  expansi(»n  of  glaciers.  In  European  nomenclature 
Pleistocene  is  applied  to  the  period  of  time  occupied  by  these  events,  and 
also  to  the  events  themselves,  and  this  without  confusion.  In  North  Ajner- 
ica  the  later  Cenozoic  history  included  a  series  of  events  of  the  same  gen- 
eral character,  and  for  these  we  have  borro\\ed  the  name  Pleistocene,  or 
its  synonym.  Quaternary.  The  time  covered  by  these  events  may  or  may 
not  coincide  with  the  Pleistocene  period,  and  until  it  is  shown  so  to  coin- 
cide, our  imported  term  is  ambiguous.  It  is  primarily  in  the  physical 
rather  than  the  chronologic  sense  of  the  term  that  the  Upper  Lahontan 
and  the  Fossil  Lake  beds  are  found  to  be  late  Pleistocene.  Properly  to 
characterize  them  in  the  chronologic  sense — with  reference  to  the  period 
including  the  glacial  and  interglacial  epochs  of  Europe — it  is  necessary  to 
take  account  of  the  work  of  land  sculpture  and  its  relative  progress  in  dif- 
ferent places. 

When  a  surface  shaped  by  some  agent  other  than  atmospheric — a  sea 
floor,  for  example,  a  moraine,  a  shore  terrace,  or  a  terrace  modeled  by 
man — is  exposed  to  atmospheric  agencies,  its  sculpture  begins.  For  a  long 
time  its  original  feattires  continue  to  be  the  characteristic  ones,  but  they 
eventually  become  subordinate  and  finally  disappear.  The  original  foriTis 
at  first  are  new  and  fresh,  then  old,  worn,  and  hard  to  discover;  and  finally 
the  fact  that  they  once  existed  can  be  known  only  from  the  internal  structure 
of  the  deposits  to  which  they  belonged.  So  long  as  the  original  form  is 
discernible,  it  yields  to  the  geologist  evidence  of  relative  newness  or  rela- 
tive age.  Such  evidence  as  this  is  not  readily  formulated,  but  it  is  con- 
stantly employed  by  the  field  geologist  in  the  study  of  the  surface.  Indeed 
it  affords  one  of  the  most  important  liases  of  tlie  wide  spread  opinion  tliat 
glaciation  was  simultaneous  in  Europe  and  America. 

The  abandoned  lake  shores  of  Christmas  Valley  and  of  the  Lahontan 
Basin,  the  lacustrine  plains  below  them,  and  the  correlated  glacial  moraines, 
are  all  of  youthful  habit,  as  youthful  as  the  "parallel  roads"  of  Glen  Koy 
and  other  surface  features  marking  the  wane  of  glaciation  in  Scotland. 
The  lake  shores  and  sea  shores  associated  with  tlie  latest  Pliocene  beds  of 


COMl'AKATIVE  SUULPTUKE.  397 

Europe  are  eitlior  iinrecog-nized,  or  else,  as  in  the  case  of  the  Enghsh  Cray, 
known  only  by  their  internal  structure.  The  plains  of  their  upper  surfaces, 
where  not  covered  by  glacial  or  volcanic  deposits,  are  either  obsolete  or 
obsolescent.  The  topogra})liy  created  in  the  presence  t)f  the  Equus  fauna 
is  young;  that  created  in  the  presence  of  the  European  Pliocene  fauna  is 
old.  With  the  aid  of  this  additional  link  in  the  chain  of  physical  evidence, 
the  geologist  ties  the  Equus  fauna,  not  merely  to  the  American  glacial  or 
Pleistocene  history,  but  to  the  Pleistocene  time  division. 

The  ancient  Lake  Bonneville,  the  ancient  Lake  Lahontan,  the  ancient 
lake  of  the  Mono  Basin,  the  ancient  lake  of  the  Christmas  Lake  Basin,  and 
numerous  smaller  extinct  lakes  of  Oregon  and  Nevada,  are  tied  together  by 
community  of  physical  characters — freshly  bared  sediments,  conforming  to 
the  slopes  of  surface  and  surrounded  by  freshl}-  formed  shore-lines.  Many 
have  yielded  shells  of  recent  species.  Two,  those  of  the  Lahontan  and 
Christmas  lake  basins,  have  yielded  the  same  mammalian  fauna.  The 
two  largest,  Lahontan  and  Bonneville,  have  yielded  detailed  and  parallel 
physical  histories.  The  analysis  of  climatic  factors  correlates  them  with 
ancient  glaciation  in  neighboring  mountains,  and  their  shores  are  carved 
from  and  built  around  late-formed  moraines  of  the  Wasatch  Rangre  and  the 
Sierra  Nevada.  The  detailed  history  shows  two  lacustral  epochs  corre- 
sponding to  two  glacial  epochs,  and  correlates  the  mammalian  fauna  with 
the  later  half  of  the  later  glacial  e[)i)ch.  Presumptively  this  date  falls  very 
late  in  the  Pleistocene  period.  The  phenomena  of  comparative  sculpture 
show  that  it  is  at  least  later  than  tlic  latest  Pliocene  of  Europe. 

THE  PALEONTOLOGIC   EVIDENCE, 

So  far  as  I  am  aware.  Cope  alone  has  stated  the  jjaleontologic  grounds 
for  referring  the  Equus  fauna  to  tlie  Pliocene.  Comparing  it  with  the  sub- 
Appenine  fauna  of  Europe  (Pliocene),  he  says— "The  characteristic  of  this 
fauna  is  the  fact  that  the  species  belong  mostU'  to  existing  genera.  .  .  In 
the  Equus  beds  of  Oregon,  a  few  extinct  genera  in  like  manner  share  the 
field  with  various  recent  ones,  while  not  a  few  of  the  bones  are  not  distin- 
guishable from  those  of  recent  species."  Li  a  succeeding  paragraph  he 
adds:  "As  a  conclusion  of  the  comparison  of  the  American  Equus  beds  in 


398  LAKE  BONNEVILLE. 

general  with  those  of  Europe  it  may  be  stated  that  the  number  of  identical 
genera  is  so  large  that  we  may  not  hesitate  to  [)arallelize  them  as  strati- 
grapliioallv  the  same.'" 

Three  eategories  of  evidence  are  here  used:  (1)  the  relative  abundance 
of  extiuft  genera  in  the  two  faunas,  (2)  the  relative  abundance  of  extinct 
species  iu  the  two  faunas,  (3)  the  abundance  of  genera  common  to  Ijoth 
faunas. 

The  first  and  second  categories  embody  the  nu;thod  devised  by  Lyell  for 
the  classifit-ation  of  Tertiary  formations,  a  inetliod  Ijased  on  the  })ercentage 
in  each  fauna  of  living  or  extinct  forms.  Faunas  with  the  hjwest  per  cent  of 
recent  forms  were  grouped  together  as  Eocene,  those  with  a  certain  higher 
per  cent  were  called  Miocene,  and  so  for  the  Pliocene.  The  method  rests 
on  a  generalization  from  observation  and  on  a  postulate.  The  generaliza- 
tion is  that  from  the  earliest  Eocene  time  the  fades  of  life  has  "■raduallv 
approached  the  present  fiicies.  The  postulate  is  that  the  rate  of  change  has 
been  uniform  in  all  places.  If  the  postulate  is  true,  the  method  of  L\-ell 
can  yield  exact  time  correlation;  otherwise  it  can  }'ield  only  approximate 
time  results.  Lyell  himself  disclaims  belief  in  the  postulate  and  regards 
his  classification  as  cln-onologically  imperfect.^ 

'These  passages  occur  ou  pages  47  and  48  of  a  paper  on  Thu  Kelatiousof  the  Horizous  of  Extinct 
ViTtel>rata  of  Eiirupo  ami  North  America,  ]mbli,she(l  in  volume  V  of  the  Bulletins  of  the  IT.  S.  Survey 
of  the  Tirritoiies.  Ou  paj;e  4'.)  the  correlation  of  the  Eiiuns  beds  with  the  Pliocene  is  characterized 
as  the  "exact  idcutilicatiou  "  of  a  restricted  division.  The  autlior's  conlidence  iu  the  correlation  was 
not  materially  shaken  by  a  pridiininary  statenieut  of  the  physical  evidence  made  by  the  writer  to  the 
National  Academy  of  Science  iu  1886.  See  American  Naturalist,  vol.  \.\I,  18-i7,  p.  4.jlt.  In  the  jiassa^e 
last  referred  to  Cope  says:  "This  gentleman  [Gilbert]  has  expressed  the  belief  that  the  beds  of  this 
age  are  not  older  than  the  glacial  ejioch,  because  they  embrace  the  bases  of  some  of  the  moraines  of 
some  of  the  ancient  glaciers  of  the  Sierra  Nevada.  It  remains  to  be  proven,  however,  that  these 
moraines  are  of  true  glacial  age,  since  they  are  of  entirely  local  character.  The  preseuco  of  so  many 
mammals  of  the  fauna  of  this  valley  of  Me.xico  would  not  support  the  belief  iu  a  cold  climate." 

When  the  moraines  referred  to  were  lieing  formed,  the  Sierra  Nevada  bore  eu  its  back  a  mer-de- 
glace  as  extensivi;  as  that  of  the  Alps,  and  a  host  of  glaciers  llowed  from  this  to  the  valleys  below, 
reaching  altitudes  from  (i,(IOII  to  ",),000  feet  lower  tiian  the  littli>  glaciers  that  now  cling  to  a  few  of  its 
peaks.  At  the  sane^  time  there  were  also  great  glaiuers  lu  the  Wasatch  Mountains.  Whatever  infer- 
ences these  phcncMuena  yield  as  to  the  contemporaneous  climate  of  \\w.  Great  Hasin  a])pears  to  me  ipiiti' 
independent  of  the  question  of  thinr  correlation  with  a  glacial  ep  leh  souu'where  else.  If  the  glaciers 
prove  a  cold  climate  iu  the  Great  Basin,  then  the  animals  that  Icit  their  bones  in  the  contemporaneous 
lake  sediments  of  the  Basin  lived  iu  a  cold  climate.  If  the  animals  could  not  live  iu  a  cold  climate, 
then  it  is  shown  that  the  valleys  of  the  Great  Basin  were  warm  despite  the  icoou  the  high  ii.onntains. 
The  question  ot'  geologic  date  is  not  involved. 

The  value  of  the  Ecpius  fauna  as  an  index  of  contemporaneous  climate  has  already  been  discussed 
in  chapter  VI  of  this  volnmi'. 

■'Sir  Charles  Lyell.     M.anual  of  Geology,  IJth  ed.     New  York.     p.  III!. 


METHODS  OF  PALEONTOLOGIO  CORRELATiOISl.  399 

The  third  category  of  evidence,  the  abundance  of  common  elements  in 
two  faunas  compared,  is  that  ordinarily  used  in  paleontologic  correlation, 
and  it  aj^plies  to  the  older  formations  as  well  as  to  the  Cenozoic.  The 
method  of  using  it  is  analogous  to  the  assignment  of  commercial  colors  to 
their  approximate  positions  on  the  prismatic  scale,  and  may  be  character- 
ized as  a  method  of  matching.  Having  in  one  district  a  number  of  faunas 
determined  by  physical  relations  to  be  successive,  the  paleontologist  com- 
pares a  single  fauna  of  another  district  with  each  of  these  severally  and 
"  correlates  "  it  with  tlie  one  with  whicli  it  has  most  in  common.  The  prin- 
cipal check  on  this  method  lies  in  the  consistency  or  inconsistency  of  its 
results  with  one  another.  When  two  faunas  of  one  district  are  separately 
compared  with  the  faunal  scale  of  another  district,  their  relative  ages  as 
inferred  from  the  results  of  matching  is  usually  the  same  as  shown  by  their 
physical  relations,  but  there  are  a  few  exceptions  to  this.  Again  wlien 
l)iotic  data  of  two  or  more  kinds,  as  for  example  vertebrate  fossils,  inverte- 
brate fossils  and  fossil  plants,  are  separately  employed  for  correlation  by 
matching,  the  results  are  often  accordant,  but  they  are  also  often  discord- 
ant. How  far  the  discrepancies  of  result  are  due  to  imperfection  of  method 
and  how  far  to  imperfection  of  data,  is  not  known,  but  it  is  generally 
admitted  that  there  are  limits  to  the  applicability  of  the  method.  The 
greatest  discrepancies  in  its  resuhs  liave  been  found  wlieu  the  formations 
compared  lie  far  apart,  so  as  to  fall  in  different  faunal  j)rovinces;  audit 
may  be  said  in  general  that  its  value  varies  dii'ectly  with  the  degree  of 
resemblance'of  the  faunas  compared.  Where  the  whole  number  of  common 
forms  or  of  common  types  is  small,  cttrrelation  is  less  precise  than  where 
the  lunnber  is  large. 

In  order  to  gauge  the  Equus  fauna  by  the  accepted  scale,  I  iia\e 
selected  a  series  of  European  faunas  more  or  less  restricted  geographically 
and  of  well-known  age.  They  are  (1)  the  Lower  Pliocene  of  Montpellier, 
France,  (2)  tlie  Upper  Pliocene  of  the  Arno  Valley,  Italy,  (3)  the  Pleisto- 
cene of  Great  Britain,  (4)  the  living  fauna  of  Europe.  The  genera  and 
species  of  the  land  mammals  of  these  faunas  have  been  compared  with 
those  of  the  Equus  fauna  and  the  accompanying  ta]:)le  constructed. 


400 


LAKE  BONNEVILLE. 


The  table  includes  only  mammalian  faunas.  Cope  has  reported  from 
the  same  Oregon  locality  ten  species  of  birds'  and  two  of  fishes,^  but  these 
are  not  at  present  available  for  purposes  of  correlation.  As  it  is  known 
that  the  general  rate  of  evolution  differs  in  different  classes  of  animals,  the 
entire  Fossil  Lake  fauna  can  not  be  considered  together.  The  birds  can 
not  be  separately  used  because  of  the  scantiness  of  avian  data  in  the  Euro- 
pean faunal  scale.  The  fishes  are  themselves  too  few  for  profitable  com- 
parison. 


Table  XVII.— Summary  of  Paleontologic  Data  for  Ike  Determination  of  the  Age  of  the  Equua  Fauna. 


TciTustrial  mamnjaliau  fauDas. 

Available  for  com- 
pariBon. 

Method  of  Lyett.— 
Peicentace  of  ex- 
tinct 

Method  by  match- 
ing.— Xutubi-r  in 
cui'ntnnn  with  the 
Eiimirt  fiiiina. 

genera,      speciea. 

genera. 

ypeciea. 

genera. 

species. 

mauy    |     many 

27               48 

9  '             13 

18                29 

14                 15 

0 

7 

*n 

0 

19 
69 

4 
6 

1 
2 

Pkiatiiceno  (Great  Britain)' 

UpptT  Pliocene  (Val  d'Arno)*.. 
Lower  Pliocene  (Moutpellier)*... 

11 

21 

100 
100 

«6                   0 
2                   0 

<  Britisli  Pleistocene  Mammalia.    By  W.  B.  Dawlsins  and  \V.  A.  Sanfonl.    Palaeontographical  Society,  vols.  18  and 

32,  1866  and  1878. 

Plcistocei.o  climate,  etc.     By  W.  Boyd  Dawkin.i,  Pop.  Sci.  Review,  vol.  10,  1871,  pp.  388-397. 

'V.  I.  Forsyth  Major.     Atti  Soc.  Tosc.  Sci.  Xat.,  vol  1,  pp.  39-40  and  "Proc.  verb.,"  vol.  1,  p.  v. 

^Gervais,  quoted  by  Major.     Atti  Soc.  To.hc.  Sci.  "Nat.,  vol.  1.  pp.  224-225. 

*ln  a  publication  Hubaequent  to  the  one  tin  wiiicli  Ibis  table  is  b.aaed.  Cope  cstablislies  a  now  genus,  Holomenucug, 
to  which  ho  transfers  the  species  o(  Ajichenia  in  the  Equus  fauna.  This  doubles  the  number  of  e.\tinct  genera  in  tlie  fauna 
and  rai8e,s  its  percentage  fioni  U  to  22. 

^Tliis  number  includes  the  genus  iufra,  which  is  not  reported  from  this  formation.  As  it  is  reported  from  Ihe 
preceding  and  following  formations,  its  existence  at  that  time  can  not  be  questioned. 

The  numerical  results  by  the  matching  method  appear  in  the  two  col- 
imms  ;it  tlie  right.  The  six  geneni  of  tlie  Equus  fauna  foxmd  in  the  upper 
Pliocene  are  identical  with  those  of  the  Pleistocene,  and  include  those  of 
the  lower  Pliocene  and  living  faunas.  The  two  genera  found  in  the  Pleis- 
tocene l>ut  not  in  the  living  fauna  of  Europe  are  Equus  and  ElvpJias,  which 
persist  in  other  continents.  One  species,  Castor  fiher,  is  conuuon  to  the 
Equus,  Pleistocene,  and  Recent  faunas.  EJcphds  jmmigenius,  common  to 
the  Eqiuis  and  Pleistocene,  is  said  to  occur  in  Europe  exclusively  in  the 
Pleistocene.     The  evidence  from  genera  is  ambiguous.     That  from  s])ecies 


>  Bull.  U.  S.  Survey  Terrs.,  vol.  4, 1878,  p.  369. 


«Americau  Naturalist,  vol.  12,  1878,  p.  125. 


THE  PALEONTOLOGIO  EVIDENCE.  401 

tends  to  correlate  the  Equus  fauna  with  the  Pleistocene  of  Great  Britain, 
but  the  number  of  common  foiTns  is  so  small  that  their  testimony  lias  little 
\\'eight. 

The  numerical  results  by  the  Lyellian  method  a])})ear  in  tiie  middle 
pair  of  colunnis.  The  Equus  fauna  agrees  with  the  Up})er  Pliocene  in  its 
ratio  of  extinct  genera;  and  in  its  ratio  of  extinct  species  it  stands  rather 
nearer  the  Pliocene  than  the  Pleistocene.  Tlie  evidence  from  genera  is 
weakened  by  the  fact  that  the  numbers  involved  are  very  small;  of  9  gen- 
era from  Fossil  Lake  1  is  extinct,  of  1<S  from  the  Arno  Valley  2  are  extinct; 
tile  discovery  of  a  few  more  bones  might  cause  A\i<le  di\'ergence  of  the 
ratios.  The  evidence  from  species  is  hard  to  interpret,  because  all  of  the 
Pliocene  species  are  reported  extinct.  Does  a  fauna  with  one-third  of  its 
forms  living  stand  nearer  to  one  with  no  living  forms  or  to  one  with  four- 
fifths  of  its  forms  living?  Perhaps  the  proper  interpretation  of  this  evidence 
woidd  assiji'M  a  date  at  the  close  of  the  Pliocene  and  be<>innin<>"  of  the  Pleis- 
tocene.  It  certainly  does  not  agree  with  the  physical  evidence  in  indicating 
late  Pleistocene. 

If  all  this  paleontologic  evidence  coidd  lie  pro])erlv  coml)ined,  giving 
each  element  its  due  weight,  the  resulting  indication  of  date  would  he 
later  tlian  tlu^  upper  Pliocene  of  the  Arno  Valley  and  earlier  tlian  the  middle 
of  the  Pleistocene  of  Great  Britain.  It  might  fall  in  an  assumed  interval 
between  the  two  time  divisions,  or  it  miglit  fall  in  tlie  earlier  part  of  the 
Pleistocene. 

At  the  very  l)est,  the  ilate  inferred  from  the  physical  tacts  and  the 
date  inferred  from  the  biotic  facts  differ  liy  more  than  half  the  extent  of 
the  Pleistocene  jieriod.  Botli  can  not  be  triie;  which  sliould  l)e  accepted? 
For  my  own  jiart  1  do  not  hesitate  to  prefer  the  physical  I'videiice  and  llie 
later  date.  I  hold  with  Lyell  that  "we  can  not  presume  tliat  tlie  rate  of 
foi-mer  alterations  in  the  animate  world,  or  the  continual  going  out  and 
coming-  in  of  species,  has  been  everywhere  exactly  ecpial  in  equal  quantities 
of  time;"  and  the  Equus  fauna  seems  to  me  to  illustrate  the  principle.  It 
may  perhaps  be  found,  wdien  the  fauna  is  much  better  known,  that  its 
features  correspond  closely  with  those  of  the  contemporary  fauna  in 
Europe,  but  for  the  present  it  appears  that  the  mammalian  fauna  of  the 
MON  I 26 


402  LAKE  BONNEVILLE. 

Groat  Basin  experienced  a  greater  change  at  the  close  of  the  Pleistocene 
tliau  did  that  of  Europe. 

In  the  study  of  tlie  Pleistocene  of  Europe,  geology  and  paleontology 
have  worked  together  with  adinii-able  results.  The  geologic  relations  have 
given  to  paleontology  tlie  sequence  of  its  faunas;  paleontology  has  recii> 
rocated  by  correlating  the  deposits  of  extrn-ghicial  regions  with  elements 
of  the  glacial  history;  and  through  such  cooperation  a  bewildering  multi- 
plicity of  data  are  being  mai'shaled  into  a  consistent  though  complex  sys- 
tem. In  America  the  same  benefit  should  result  from  the  same  coopera- 
tion. Some  Pleistocene  deposits  can  be  assigned  dates  through  their  rela- 
tions to  glaciation,  and  when  the  faunas  and  floras  of  these  are  known, 
paleontology  can  contribute  much  toward  the  discovery  of  the  Pleistocene 
history  of  districts  remote  from  glaciers.  For  this  purpose  the  Lyellian 
method  of  percentages  is,  in  my  judgment,  far  less  valual)le  than  the  method 
by  matching;  but  the  standard  scale  for  matching  should  be  an  American 
scale,  based  on  physical  studies  in  the  region  of  Pleistocene  glaciation  and 
its  immediate  vicinity.' 

'  While  these  pages  are  passing  through  the  press,  a  vohime  is  published  by  Messrs.  Felix  and 
Loiik,  cimtaiiiiug  an  account  of  Pleistocene  lacustrine  formations  in  the  Great  Valley  of  Mexico.  In  a 
general  way  the  phenonicuii  of  the  Ijonneville  and  Lahontau  basins  are  there  repealed,  but  the  history 
ot  the  climatic  oscillation  has  nut  been  fully  nuidc  out.  In  undisturbed  strata,  forniiug  a  continuous 
series  with  lake  sediments  now  being  deposited,  there  have  been  found  bones  of  thirteen  maunnaliau 
species,  and  two  of  these  species  are  identical  with  members  of  tlu^  Christ ui.-i.s  Lake  fauna.  (Beitrjigo 
znr  Geologio  und  Paliioutologio  der  Kepublik  Mexico,  Vou  Dr.  J.  Felix  uud  Dr.  11.  Leuk.  Part  1. 
Leiiizig,  18U0,  pp,  (55-06,  7y-88.) 


APPENDIXES. 


A.— Altitudes  luid  tbeir  detcrmluatiou.    By  Albert  L.  Webster. 

15. — On  the  deforiuatiou  of  the  seoiil  '»y  the  removal,  tbrousli  evaiioiation,  of  the 
water  of  Lake  Bonneville.     By  K.  S.  Woodward. 

C. — On  the  elevation   of  the   surface  of  the  Bonneville  Basin  by  expansion  due 
to  change  of  climate;    By  R.  S.  Woodward. 


403 


APPENDIX    A. 

ALTITUDES  AND  TIlEIIi  DETERMINATION. 


By  Albert  L.  Webster. 


In  connection  witli  the  study  of  the  records  of  the  ivnciont  Lake  Bonneville,  it 
hecame  a  matter  of  interest  to  ascertain  the  present  relative  altitudes  of  points  scat- 
tered alonj;-  its  fornier  perimeter.  A  comi)lete  and  thoroughly  satisfactory  investiga- 
tion of  the  subject  being'  impracticable  from  economic  considerations,  it  was  made 
■subsidiary  to  the  more  general  historic  study  of  the  lake,  and  its  results  are  accord- 
ingly incomplete  or  lacking  where  such  study  would  not  permit  of  a  more  extended 
investigation.  As  far  as  practicable  altitudes  were  obtained  of  points  representative 
of  the  entire  shoreline.  To  accomplish  this  a  large  area  of  country  had  to  be 
traversed,  and  it  was  -ifcessary  to  employ  all  available  means  and  methods  for  the 
collection  of  tlie  data.  All  heights  are  referred  for  comparison  to  a  common  datum 
l»()iiit,  arbitrarily  cliosen,  the  zero  mark  of  the  lake  gauge  at  the  Lake  Shore  bathing 
resort. 

The  measurements  and  observations  here  brought  togetlier  are  not  my  own  alone, 
but  were  made  by  many  persons  and  at  various  times.  In  the  following  pages  the 
attempt  is  made  to  ari'auge  them  in  such  order  that  the  critical  reader  can  readily 
learn  the  essential  nature  of  all  the  data  on  which  each  separate  determination  of 
altitude  is  based. 

SCHEME   OP   TABLES. 

Taule     XVIII.  Differences  of  aUitiulo  determined  by  trigonometric  oljservations. 
XIX.  Dififereuces  of  altitude  determined  Ijy  Ij.arometric  oliservations. 
XX.  Reduction  of  various  lake  gange  zeros  to  tlie  Lake  Shore  datum. 
XXI.  Gauge  records,  showing  the  height  of  the  water  surface  of  Great  Salt  Lake  at  various 

dates. 
XXII.  Ditferences  of  altitiule  from  railroad  survey  records. 

XXIII.  DitFereiJCes  of  altitude  by  special  spirit-level  determinations. 

XXIV.  Reduction  of  results  to  Lake  .Shore  gauge  zero  as  a  common  datum. 
XXV.  Comparative  schedule  of  altitudes  of  points  on  the  Bonneville  shoreline 

XXVI.  Comparative  scliednle  of  altitudes  of  j>ointa  on  the  Provo  shore-line. 
XXVII.  Comparative  schedule  of  altitudes  of  points  on  the  Stansbury  shore-line. 
XXVIII.  Ditferences  in  altitude  of  the  Bonneville  aud  Provo  shore-lines  at  various  localities. 
XXIX.  Differences  in  altitude  of  the  Provo  and  Stansbury  shore-lines  at  various  localities. 


By  reference  to  this  scheme  of  tables  it  will  be  seen  that  hypsometric  material 

403 


has  been  gathered  from  the  five  following  sources 


406 


LAKE  BONNEVILLE. 


(1)  From  deterrainatious  based  upon  trigonometric  observations. 

(2)  From  determinations  based  upon  concurrent  barometric  observations. 

(3)  From  the  records  of  the  fluctuations  of  the  present  Great  Salt  Lake. 

(4)  FroQi  the  records  of  various  railroad  surveys. 

(o)  From  especial  determinations  made  with  the  surveyor's  spirit-level. 

TRIGONOMETRIC    DATA. 

The  few  results  obtained  by  the  first  method  and  jucscnted  in  Table  XVIII  were 
derived  by  comi)utation  from  measurements  of  angles  of  elevation  and  depression 
with  accompanyiuf;-  short  base-lines.  Tiie  angles  were  measured  with  the  ordinary 
surveyor's  (ransit,  reading  to  minutes  on  the  vertical  limb.  The  base-lines  were 
measured  with  a  steel  tape. 

The  results  are  recorded  in  feet  and  tenths  of  feet,  but  it  is  not  intended  to  assert 
that  they  are  true  to  the  nearest  tenth.  They  are  probably  true  to  the  nearest  foot. 
In  combining  determinatiims  of  various  kinds  it  has  been  found  convenient  to  use  the 
same  notation  for  all,  and  the  tenth  of  a  foot  has  been  <-hosen  as  expressing  the  pre- 
cision of  the  most  accurate  of  all  the  measurements — thc^  shorter  lines  of  spirit-level- 
ing. For  the  purposes  of  the  Bonneville  investigation  it  would  be  sufiicient  to  stop 
at  the  decimal  point,  as  all  the  results  of  measurement  are  combined  with  observa- 
tions involving  an  uncertainty  of  several  feet;  i)nt  it  is  conceived  that  some  of  the 
data  may  have  other  uses,  and  for  the  sake  of  these  the  tenths  are  retained. 

Table  XVIII. — Differences  of  Altitude  deiermiind  hij  Triijntinmetrie  Olmerrntion-i. 


Vicinity  of- 

Feet. 

415.1 
301.1 
410.  7 
310.0 
3G3.0 

Dovo  Ureek  — 
Kelton 

Bonneville  abore-line  above  Prove  sbore-line 

,io 

Mallin 

do             .         .            .           .                                    

Matlin 

Snowavillo 

BAROMETRIC    DATA. 

The  section  of  country  including  the  long  southern  arm  of  the  old  bike,  now  the 
Escalante  Valley,  was  practically  accessible  to  no  better  hyiisometiic.  method  than 
that  of  concurrent  barometric  observation,  and  that  method  was  accordingly  adojited 
for  its  investigation. 

This  region  in  general  lies  two  huntlred  miles  south  of  Salt  Lake  City,  and  its 
nearest  barometric  base  was  the  U.  S.  Signal  Ofilec  in  that  city.  It  was  deemed 
advisal)le  to  establish  an  intermediate  sub-base  station  in  the  nearer  neighborhood  of 
the  field  of  itinerary  ob.servation,  to  which  to  refer  the  new  stations.  The  village  ol 
Fillmore,  lying  one  hundred  miles  sonth  of  Salt  Lake  City,  ottered  especial  natural 
advantages  for  the  location  of  snch  a  sub-base.  It  includes  within  its  limits  a  jiortion 
of  the  Bonneville  siiore-line,  thus  allowing  but  slight  disitaiity  in  altitude  iietwet-n  the 
reference  station  and  now  stations.  It  is  moreover  situated  about  midway  between 
the  southern  field  of  study  and  the  Salt  Lake  City  i)rimary  base,  and  affords,  by  the 
comparison  of  its  series  of  observations  with  that  of  the  Signal  Oflice.  a  criterion  for 
judging  of  the  value  of  results  from  the  observations  at  the  new  stations. 


HEIGHTSBY  BAROMETER. 


407 


Two  barometers  and  psycbrometers  were  left  here  in  the  charge  of  an  observer, 
Mr.  R.  II.  Smith,  from  July  29th  to  October  3ril,  1881.  U])on  the  former  of  these, 
hourly  observations  were  made  each  day  from  7  A.  M.  to  9  V.  M.  inclusive ;  ui)0m  the 
latter,  readings  were  taken  daily  at  7  A.  M.,  2  P.  M.  and  9  P.  M. 

The  Survey  did  not  establish  a  base  station  at  Salt  Lake  City,  but  made  use  of 
the  ordinary  observations  by  the  U.  S.  Signal  Service  observer.  Through  the  cour- 
tesy of  the  Chief  Signal  Oflicer  of  the  Army  we  were  furnished  with  copies  of  sucii 
])ortions  of  the  records  as  were  needed  for  our  work,  viz.,  the  readings  of  barometer, 
thernioineter  and  psychronieter  at  7  A.  M.,  2  P.  M.  and  9  P.  M.,  during  the  period 
covered  by  the  observations  at  Fillmore. 

The  altitude  of  the  sub-base  above  the  Signal  Ofth^e  at  Salt  Lake  City  was  coni- 
l)uted  from  a  selected  portion  of  the  concurrent  oi)servations  at  the  two  plaiies. 

In  order  to  avoid  observations  affected  by  abnormal  atmosi)heric  conditions,  the 
"reduced"  barometric  readings  at  the  two  stations  were  platted  gra|)hically  in  close 
proximity,  with  a  common  time  scale.  A  marked  parallelism  of  the  resulting  curves 
between  the  dates  of  July  29tli  and  August  17th  led  to  the  acceptance  of  the  recoids 
included  between  those  dates  as  a  basis  for  the  computation,  and  they  alone  weie 
employed. 

Three  somewhat  independent  results  were  obtained  for  tlie  difference  of  altitude 
by  considering  sei)arately  the  means  of  the  7  A.  M.,  2  P.  M.,  and  the  9  P.  M.  reduced 
readings  at  the  two  stations,  Williamson's  method  and  tables  being  employed.*  In 
each  determination  the  terms  t+t'  and  a  +  a'  are  identical,  being  derived  from  the 
means  of  tlie  temperature  and  humidity  terms  of  the  7  A.  M.,  2  P.  M.,  and  9  P.  M. 
records  for  the  selected  period. 


7  a.  HI. 

2  p.  m. 

9  p.m. 

k.  Me.in  of  rrdiicol  readings  :it  Salt  Lako  City 

II.  Mn:in  of  reduced  rcadinjis  at  Fillmoro    

Inr.hrtt. 
2.'i.  (ifi8 
24.947 

Fret. 
24,  720.  9 
23,  973. 8 

Tvekea. 
2.)  041 

21.  91)7 

Fret. 
24,  693.  2 
21,931.7 

Inehes. 
2.-).  013 
24.81)8 

Fret. 
24.004.6 
23,  922. 3 

t+t'  from  means  of  7  a.  m.,  2  p.  m.,  and  !)  p.  ni.  tem- 
perature reading.s  at  Salt  Lake    City  and  Fillmore  ~ 
1510.92  F. 

a  +  a'  fi-om  moans  of  7  a.  in.,  2  p.  m  .  ami  9  p.  m.  rela- 
tive humidity  reiluctions  for  Salt  Lake  City  and  Fill- 
more =  0.60. 
From  Table  l>i  with  argument  h 

First  approximate  difl'ercDce  of  altitude 

From  Table  Dii 

747.1 
+66.  80 

761.  5 
+08.  15 

742.3 
+06.44 

813.  90 
-h6.21 

829.  05 
+0.32 

808.  74 
-1-6.14 

Tiibles  Dili  to  D,ii,  inclusive,  with  general  arsumrnts  (  +  (' 
=  151°.92  F.,  a  +a'=  0.60,  lat.=  40°,  and  seoond  ajiproxi- 
mate  dilTerence  of  altitude,  give  additional  correction  . . . 

820.  17 

835.  97 

814. H8 

Accepted  result,  mean  of  tlie  three  determinations, 
823.7  feet. 

'Professional  papers  of  the  Corps  of  Engiuccrs,  U.  S.  Army.     No.  15,  Appeudix. 


408 


LAKE  BONNEVILLE. 


To  the  Fillmore  station  alone,  as  a  base,  have  been  referred  all  the  itinerary 
barometric  records  taken  in  tlie  district  south  of  it. 

At  the  new  stations  no  *'dry  bulb"  thermometer  or  psychroraeter  readiufj^s  were 
talvon,  and  wliere  such  diita  were  necessary  in  the  comi)utation  of  their  altitu<les  they 
were  snpidied  from  the  Fillmore  records  alone. 


Tablk  XW.— Differences  of  AUiliide  determined  from  Barometric  Observations. 


Vicinity  of 


Antelope  Spring 
(Lower  Kscalaute 
Uosert). 

Fillninro 


Giantsvillo   

Kaiiosli 


Meadow  Creek 


Point  :in<l  liefi-rt-nce. 


North  Twin  Peak.. 

Pavant  Butte 

Pinto  Canyon 

Shoal  Creek 

South  Twin  Peak.. 

Siilplmr      Springs 

(Ertoalanto  Desert) 

Thermos 


White  HouDtain. 


P.onneville  >*hoie-line,  1  mile  west  of  Spring,  altove  Fillmore  anb- 
ba.se  harOTueter. 

Sub-ba.se  cistern  barometer  rtbrice  H.  S.  Signal  Office  barometer  at 

Salt  Lake  City,  Utah. 

Bonneville  shore-line  above  Provo  shore  line 

Bonneville  .shoreline  on  Kannsh  Bnttf  hil»w   Fillmore  anb-base 

barometer. 
Bonneville  .shoreline,  1  mile  east  of  tiitrance  to  canyon,  above 

Fillmore  sub-base  barometer. 
Bonneville  shore-line,  1   mile  west  of  entr.ince  to  canyon,  above 

Fillmore  sub-base  barometer. 
Camp  on  east  bank  Beaver  River,  hehnv  Fillmore  sub  base  batom- 

etcr. 
Bonneville  aliore-line,  1  mile  northwest,of  Alilfonl,  below  I-'illmore 

anb-haae  barometer. 
Bonneville  sbore-line,  7  miles  south  of  Milfonl.  below  Fillmore 

sub-base  barometer. 
Bimneville  ahore-line,  east  base  of  Peak,  aboiw  Fillmore  sub  base 

barometer. 
Bonneville  ahorc-lino,  ca.st  baseof  Butte,  below  Fillmore  sub-base 

barometer. 
Bonneville  sliore-line.  west  of  entrance  to  canyon,  above  Fillmore 

Mub-ba.se  harometer. 
Bonneville  shctre-line,  north  of  entrance  to  canyon,  above  Fillmore 

riuh  bxso  barometer. 
Bonneville  almre-line,  west  base  of  Peak,  below  Fillmore  sub  base 

barometer. 
Bonneville  shore-line  above  Fillmore  suli-hase  harometer 


DitlVrence 
in  Altituile. 


Bonneville  shore-line,  2  miles  east  of  Springs,  behnv  Filhiioie  sub- 
base  baronuiter. 

Bonneville  Nhore-liue,  4  miles  south  of  Springs,  below  Fillmore 
sub-base  barometer. 

Bonuevilh>  shore  line.  7  miles  south  of  Si)rings,  below  Fillmore 
aub-base  liarometer. 

Camp,  belo7t>  Fillmore  suhbuae  barometer 


Feet. 

3fl.  7 


ft2:t.7 

381.3 
17.3 

296.  G 

294.5 

21P.6 

7fi  0 

48.  J> 

L2 

67.6 

214.1 

26.-..  ri 

.12,5 

45.2 

76.6 

48.7 

42.1 

474.1 


.HEIGHTS  B-Y  BAKOMETEK.  409 


LAKE    RECORDS. 

At  various  times  spirit  lovol  lines  Iiare  been  run  from  the  surface  of  Great  Salt 
Lake  to  points  on  the  ancient  beaches  in  tlie  near  nei^liborbood  of  its  present  shore. 
The  records  of  altitudes  thus  obtained  are  not,  however,  directly  comparable,  suice 
the  surface  of  the  lake  is  in  a  state  of  continual  fluctuation,  the  records  of  which  have 
lieen  referred  to  independent  jjauges.  It  was  accordingly  nece.'sary  to  determine  pii- 
marily  the  relative  altitudes  of  the  zeros  of  the  various  gauges. 

Previous  to  1875  the  record  of  the  rise  and  fall  of  the  lake  is  iturely  a  tradition;il 
one.  Such  evidence,  however,  as  is  reliable,  has  been  presented  by  Mr.  Gilbert  in  his 
chapter  on  "  Water  Supply,"  Powell's  "  Lands  of  the  Arid  Region,"  in  which  the  rec- 
ords have  been  referred  to  the  level  of  the  Antelope  Island  Bar  as  a  datum.' 

In  1875  a  granite  inonuineiit,  graduated  to  feet  an<l  inches,  was  eretited  by  Dr. 
John  R.  Park,  of  Salt  Lake  City,  at  Black  Hock  on  the  southern  shore  of  the  lake,  and 
upon  this  observations  were  made  at  intervals  until  October  9th,  1876,  when  it  was 
abandoned.  Li  connection  with  it,  the  Powell  Survey  jdaced  a  granite  bench  block 
on  the  shore  near  iiy.  A  line  of  spirit-levels  was  subsecjuently  run,  which  showed  the 
Black  Rock  MonunuMit  zero  to  be  36.5  feet  below  the  Black  Rock  Bench. 

In  1877  another  gauge  was  erected  at  Farmiugton,  on  the  east  shore  of  tlie  hike, 
in  nil  inlet.  A  stone  reference  point,  planted  on  rising  ground  near  by,  and  known 
as  the  Farmiugton  Bench,  was  found  to  be  12.9  feet  above  the  zero  of  the  Faniiington 
gauge.  Observati(>ns  were  made  at  intervals  on  the  newly  erected  giuige  until  Octo- 
ber, 1879,  when  it  was  rendered  useless  by  the  occurrence  of  a  succession  of  hea\y 
winds  from  the  westward,  which  effectually  barred  the  entrance  of  the  inlet  witii  sand, 
thus  cutting  ofl'  its  direct  cominunicatiou  with  the  lake.  In  anticipation  of  such  an 
occurrence,  a  third  gnnge  had  been  established  at  Lake  Shore,  live  miles  soiitii  of 
Farmiugton,  and  monthly  records  begun  November  19th,  1879.  This  is  known  as  the 
Lake  Sliore  Gauge,  and  to  its  zero  as  a  datum  have  been  referred  the  various  deter- 
minations of  which  tiiis  ai)pendix  treats.     (See  Table  XXIV.) 

A  general  taliing  tendency  of  tlie  Lake  for  several  years  portended  disqualifica- 
tion of  this  gauge,  and  rendered  the  erection  of  a  deeper  set  scale  a  matter  of  pieciin 
tionary  advisability.  A  fourth  gauge  was  accordingly  established  at  Garfield  Land- 
ing, three  miles  west  of  Black  Kock.  It  consists  of  a  stout  strip  of  scantling,  nine- 
teen feet  long,  firmly  si>iked  to  one  of  the  piles  of  the  steamer  pier.  It  is  graduated 
to  feet  and  iiicbes.^ 

On  the  23d  of  -luly,  ISSl,  the  Black  Rock  bench  was  found  by  spirit  level  to  be 
38.7  feet  above  the  surface  of  the  lake;  at  the  same  time  the  water  washed  the  7  ft. 
9  in.  mark  of  the  Garfield  gauge.  Thus  the  zero  of  the  latter  is  4G.4  feet  below  the 
Black  Rock  bench. 

Table  XX  indicates  the  steps  by  which  the  various  gauges  have  been  reduced 
to  the  Lake  Shore  zero. 

'Ttie  traditional  record  is  repeated,  with  an  addition,  in  this  volume,  pp.  2:W-243.     G.  K.  G. 
^Since  tlie  preparation  of  this  Appendix,  the  Garfield  gauge  has  been  destroyed  and  renewed 
Oee  p.  232.    G.  K.  G. 


410 


LAKE  BONNEVILLE. 


Table  XX. — Reduction  of  various  Lake  Gauge  Zeros  to  the  Lake  Shore  Datum. 


Point. 

Intermediate  Datum. 

Uato. 

Refi^ned  to 

Intermediate 

Datnm. 

Referred  to 
Lake  Slioro 
Gauge  Zero. 

Jan. 2:1, 1880  ... 

+  2.r< 
+  3.8 

A   "Temporary  Bpnrh''  ,it 
Farmington. 

Lako  Surface 

do      ... 

+  1.3 

Farmington  Gauge  Zero 

A    "Temporary  Bencli  "  at 
Farmington. 

Nov.  .■!,  1879     . . 

-  0.1 

+  3.7 

Farmington  Gauge  Zero 

do 

+12.  n 

fie.G 

+  2.0 

M!»r.  21  lo  Mot. 
25,  1881. 

Qarfield  Landing  Gauge  Zero 

Mean  Lake  Surface 

..  do 

-  7.2 

-  4.6 

Lake  Surface 

G.arfifld  Landin" Gange Zero 

July  23,  1881  .  .  . 

+  7.7 

+  3.1 

Black  Hack  Bench  

do 

+38.7 
-34.5 
-  2.0 
+     .8 

+41.8 
+  7.3 
+  5.3 
+  0.1 

Lake  Surface 

Black  Rock  Monument  Zero.. 
Lake  Surface 

IJlaclt  liock  Bencli 

July  12,  1877    .. 
.  do 

Lake  Surface 

Black  Rock  Monument  Zero 

Oct.  10,  1877  .   . 

Antelope  Island  Bar  in  tlio 

Lako  Surface    

....do  

-  0.5 

-  3.4 

"little  cbannel." 

A  uote  of  uncertainty  relative  to  tlie  results  depenilent  on  the  Black  Bock  ob- 
servation of  July  12,  1877,  must  be  introduced  here.  The  observer's  record  of  that 
observation  reads  as  follows: 

Jut)/  12,  1877. — Water  washed  higbest  font  mark  of  graduation  on  Dr.  Park's  [Black  Rock]  iiion- 
iinient ;  supposed  to  bo  the  two-foot  mark. 

The  scale  is  neither  numbered  nor  lettered,  but  subsequent  conversation  witli 
Dr.  Park  led  to  the  acceptance  of  the  record  in  conformity  with  the  su[)position  of  the 
observer. 

Confirmatory  evidence  is  found  in  the  close  agreement  of  this  determination  of 
the  monument  zero  with  a  second  determination,  which  joins  t)ie  monument  zero  to 
the  Farmington  zero  by  reference  to  the  lake  surface.  The  difference  in  the  two 
results  is  less  than  two-tenths  of  a  foot.  As  an  interval  of  fifteen  hours  elapsed 
between  the  readings  of  the  two  gauges  the  second  determination  was  considered 
only  as  a  general  check  for  large  errors,  and  was  not  used  in  the  reduction. 

A  table  and  platted  curve  showing  the  rise  and  fall  of  the  present  (Jreat  Salt 
Lake  from  September,  1875,  to  June,  1889,  will  be  found  on  pages  233-243  of  the  mono- 
graph of  which  these  pages  form  an  appendix.  By  means  of  the  data  contained  in 
that  table  the  lines  of  leveling  at  various  times  connected  with  the  water  surface  of 
the  lake  were  referred  to  the  Lake  Shore  gauge  zero.  The  specific  data  thus  used  are 
here  repeated  in  Table  XXL 


HEIGHTS  OF  LAKE  SURFACE. 


411 


Table  XXI. — Gauge  Records,  showing  the  height  of  the  Water  Surface  of  Great  Salt  Lal;e  at  various  dates. 


Gauge. 

Date. 

Ri'adinji. 

Hciulit  ..f 

Trauiio  Zoro 

aliovn  Zi'io  of 

Lake  Shore 

Gauge. 

Height  of 

Water  Sui  fare 

ahove  Zi'io  of 

Lake  Shore 

Gauge. 

Rlack  Rock 

Do  

Fannington  

LaUe  Shore 

Do 

July  12,1877.. 
Oct.  19.  1877  . . 
May  2,  1879    .. 
Nov.  9.  I87!>... 
Nov.  12, 1880.. 
Nov.  29,  1880  . . 
Dec.  11,  1880... 

Ft.   In. 
2      0 

0  10 

1  4 

2  G 
1       9 
1       8J 
1      8J 

Feet. 

.'i.  n 
.1.7 

IF 

0 
0 
0 

Feel. 
7.3 
0.1 
.I.O 
2.5 
1.7 
1.7 
1.7 

Do.  ..   , 

Do 

RAILROAD   RECORDS. 

A  fourth  .source  from  wliicli  data  liave  l>i>cii  obtained  to  assist  in  the  general 
comi)i!ation,  is  Found  in  the  records  of  various  railroad  surveys.  Tiie  results  appear- 
inj;  in  Table  XXII  in  some  eases  have  been  derived  from  Gannett's  "  Lists  of  Eleva- 
tions", 1877,  and  such  are  indicated  by  a  star  (*);  iii  other  cases  they  are  from  tran- 
scripts of  official  profiles  kindly  furnished  by  the  engineers  of  the  dittereut  roads. 


TAni.n  XXII. — Differences  of  Attilude  derived  from  Railroad  Surrey  Records. 


Vicinity  of 

Poiuts  Dutorinincd  anil  Poiuts  of  Kcferonco. 

Feet. 

Corinne  Station  (Central  Paciflc  R.  R.)  below  Ogilen  St.ation 

Franklin  Station  ( Utah  Nortliern  R.  R.)  alioite  0;;<ieu  Station    

Leniington  Station   (LTtah   Southern    K.  K.  extension)    above  Salt 
Lake  City  Station. 

71.3* 

213.0 
456,0 

20n.  0 
707.5 

42,  3* 
517.0 
280.  0 
773.0 
287.0 
551.0* 

Logan  

Milfonl 

Milfonl  .Station  (Utah  Simthoru  R.  R.  extension)  above  Salt  Lake 

City  Station. 
Ogden  Station  (Utah  Central  R.  U  1  aboiie  Salt  L.ake  City  Station. .. 

Summit  (Utah  Southern  R.R.)  atom- Salt  Lake  (.:ity  Stat i  mi 

Reil  Rock  Gap  Station  (TTtah  Northern  R.  R.)  above  Franklin  Stalimi 

Snnimit  (U.  S.  R.  R,)  above  Salt  Lake  City  Station  (U.S.  R.  R.) 

Swan  Lake  St.ation  (Utah  Northern  R.  R.)  above  Franklin  Station  .. 
lecoina  Station  (Cential  I'aeitie  R.  R.)  ahovc  Salt  Lake  City  Station 

(U.S.  R.  R.). 

Point  of  thi^  Mountain 
Red  llock  Gap    

SPECIAL  SPIRIT-LEVEL  DETERMINATIONS. 

Table  XXIII  contaius  the  results  of  spirit-level  determiuatioiis,  made  with  espe- 
cial reference  to  the  study  of  the  ancient  lake.  Check  lines  have  been  run  wherever 
practicable,  and  the  mean  of  the  origiual  and  duplicated  work  accepted.  IJesults 
thus  verified  are  marked  by  a  star  (*)  in  the  table. 

Measurements  made  with  Locke's  hand  level  are  marked  thus  (t). 


412 


LAKE  BONNEVILLE. 


Table  XXIII. — Differences  of  Altitude  hij  Special  Spirit-Level  Determinationt. 


Vicinity  of 

Points  and  References. 

Feet. 
1059.0 

Aqni  K:inj:o,  Nortln-iiil 

lioiinoville  .shore-linn  above  lake  siirrace,  .Inly  2i<,  1877 

Provo  Hhorc-titie  above  lalio  surface,  July  28,  1877 

678.0 

Ilonnevillo  .sliore-liiie  tifcnwr  liiko  flui-face,  Nov.  25, 18S0  

1058.  4» 

Provo  sliure-Iiuo  above  lake  .tuiface,  Nov.  25,  1880 

G7C.9 

Stm.Hlmry  slioro-liue  above  laUo  surface,  Nov.  25,  1880 

.331.0 

Blank  Knck 

liiiuiievilliisljori;-liuf,  above  lake  aiirfnco,  .Inly  12,  1877 

>.m.  0 

HIack  liock  Itench  above  Black  Rock  Monument  zero  

34.  B 

Provo  shore-line  ofiorc  lake  aurfacc,  July  12,  1877 

033.  U 
247.0 

.Stauftbury  shore-lini'  above  lake  surface,  July  12,  1877  

Corinne  Station  (C.  P.  11.  It.)  above  lake  snrfac  o.  May,  1873,  (Wliechr 

22.6 

Cup  Butte 

l-'illiiiore 

IJonnoville  ahoro-lino  above  Provo  sliort>-line 

397.01' 

19.4' 

309.  01 

Finli  Spring 

Uunne\ille  cut- terrace  above  Prove  cut-terrace 

Bonneville  shore-line  on  Franklin  liutte afcorc  l''raiiKliii  Station  (U. 
N  i:.  R) 

KG.O 

Provo  .shoreline  on  Franklin  Bntte  above  Franklin  Stariou  (U.N. 

R.K.) 

201.  0 

Kelton 

Bonneville  .shore  lino  above  lake  .surface,  Aug.  11, 1877  (checked  by 

1017.5 
,52.4' 

r.akc  Shore  GauKe  zero  below  Salt  Lake  City  Station,  tl.  S.  R.  R 

Bonneville  shore-Iiuo  above  Lemington  Station  (tJ.  S.  R.  R.  extension) 

380.  C< 

Logiin 

Bonneville  shore-line  above  Lo^an  .Station  (U.  N.  R.  R.) 

632.9 

Provo  shore-line  rttoV(?  Lo*;an  Station  (f.N.R.R.)   

270.2 

Milford 

Bonneville  shore-line  above  Millnnl  Station  (U.  S.  K.  R.  extension)  - 

152.  7  • 

Camp  on  e.ast  hank  Beaver  River  Womi  Milfor.l  Station  (U.S.  R.R. 

0>;il<-n    

7.0 

Bonneville  shore-line  above  Ogden  Station  U.  C.  R.  11.,  (Prof.  F.  H. 
Bradley,  Ilavden  Survey).   -. 

87G.  Of 
329. 1* 
358.0 

Pavant  Batte  

Point  of  the  Mountain 

Bonneville  shore-line  above  Summit  (U.  S.  R.  R.)  

Picusa  Valley 

Provo  shore-line  6eioic  Bonneville  shore  line        

375.5 
343.2* 

'Ncuth  Group,"  Bonneville  .shore-line  above  Pi  ovo  shoreline 

"  Middle  Group,"  Bonneville  shore-lino  above  Provo  shore-line 

346.4* 

Promontory 

Red  Rock  Pass 

Bonneville  shore-line  a&ore  lake  auiface,  Aug.  23,  1877    

1037.7 
«B5.  8 
303.  U 

Provo  shore-line  a&oi'c  lake  surfu'o,  Aui^.  23,  1877      ..  , 

Bonneville  shoreline  above  Swan  Lake  Station  (U.  N.  R.  R.)  

Salt  Lake  City 

Bonneville  shore. line  above  Salt  Lake  City,  Meridian  M'lnnment  ... 

845.9* 

.Meridian  Monument  below  U.  S.  Signal  Si-rvice  barometer  

12.  6* 

SaU  Lake  City  St.ation  |U.  S.  R.  R.)  Mow  Meridian  Monument  .... 

72.0* 

S.alt  Lake  City  Station  {U.S.  R.R.)  above  Lake  surface,  Dec.  11, 1881. 

50.7* 

Santaqain  

Bonneville  shore-lino  above  Sautaqnin  Summit  (U.  S.  \l.  R  ) 

75.0 

Bonneville  fthoro-line  «6f*«f  Provo  shore-line       

401.0* 
1011.0 

Stockton         

Bonneville  shoreline  above  lake  surface,  Mar.,  1873  (M.  F.  Burgess) 
Prove  shore-line  (j/'iow  Bonneville  shore-line 

375,0 

Bonneville  shore-line  above  Teronia  Station  (C.  P.  R.  R.) 

Bonneville  shore-line  aborc  Provo  shore-line                      

367.8 

Wellsrille    

AVhite  Mountain  (Fill- 

383.7 

Provo    shore-line  on  White    Mountain    above     While   Monnlnin 

more.) 

camp 

68.9 

Provo  tufa  deposits  on  Tabernacle  Bntte  Uva  bed  above  camp 

42.9 

Willard 

Bonneville  shoreline  above  lake  surface  Oct  28  1879 

974.  Ot 
621.  Of 

Provo  shore-line  above  lake  surface,  Oct.  28.  1879. 

UEIGUTS  BY  LEVELING. 


413 


COMBINATION  OF  DATA. 

lu  the  schedule  followiug  (Table  XXIV)  a  collection  and  combiuation  is  made 
of  results  appeariuj?  in  some  of  the  six  tables  preceding,  so  as  to  reduce  tlie  stations 
to  which  they  apply  to  the  arbitrarily  assumed  Lake  Shore  zero  datum.  Tiie  table  is 
arranged  with  reference  to  the  latitudes  of  the  points  determined,  beginning  with  the 
most  northerly. 

Table  X'K.IV. —Reditclion  of  Rumiltn  to  lite  Lake  Shore  Gauge  Zero  as  a  Common  Daliim. 


Point. 


L.^ke  Surfaci-,  IK-c.  1 1,  1880    

Salt  LakeCily  Sl.ilioii  (U.S.  K.  It.) 

Ogdell  Statiou    

Fraiikliu  Station  ilT.  N.  K.  R.) 

Swan  Laks  Station  (D.N.  Iv.  K.) 

Bonneville  aUore-lino,  vicinity  of  Rod  Itock  Paaa 


Franklin  Station 

HonneviUe  sbore-linf*  ini  Franklin  Butto - 
Trovo  8bore-line  on  Franklin  Butto 


OK'len  Station 

Lo2!in  StJltion  (U.  N.  E.  R.) 

Bonneville  .shore-line,  vicitiity  oT  Logan  . 
Pi-ovo  .shoi-e-line,  vicinity  of  Logan 


Lake  aui'facp,  Ang.  11, 1877;  interpolated 

Bonneville  shore  line,  vicinity  of  Kelt<ni     . . . 
I'rovo  shore-line,  vicinity  of  Kelton  


Lake  snrface,  Aug.  23, 1877;  interpolateil 

Bonneville  shore  line,  vicinity  of  Promontory 

Prove  shore-line,  vicinity  of  Promontory  

Lake  surface,  tlct.  28, 187!»;  interpolated 

Bonneville  ahore-liue,  vicinity  of  Wilhird  

Piovo  .shore-line,  vicinity  of  Willard 


Salt  Lake  City  Station  (n.S.R.R.)    

Teconia  Station  (C  P.  R.  U.)    

Bonneville  shore-line,  vicinity  of  Tecoma. 


<  )gden  Station 

Bonneville  shore-line,  vicinity  of  Ogden. 


Salt  Lake  City  Station 

Salt  Lake  City  Meridian  Monument 

Bonneville  shore-line,  vicinity  of  Salt  Lake  City 
(Ist  determination). 


Intermediate  Datum. 


Lake  Shore  Gauge  Zero  . . . 
Lake  Surface,  Dec.  U,  1880  - 

Salt  Lake  City  Station 

Ogden  Station  -   

Franklin  Station 

'Swan  Lake  Station 


Franklin  Station . 
do 


Ogden  Station  . 
Logan  Station  . 
do 


Lake  Shore  Gauge  Zero 

Lake  surface,  Aug.  11,  1877 
Bonneville  shore-line 


Lake  Shore  Gauge  Zero  . ... 
Lake  surface,  Aug.  23, 1877. 
do 


Lake  Shore  Gauge  Zero  . . . 
Lake  surfiice.  Oct.  38.  1879 
do 


Salt  Lake  City  Station . 
Teconia  Station  ... 


Ogden  Station  . 


Salt  Lake  City  Station. 
Meridian  Monument  .. 


From 
Table 


XXI 
XXIII 
XXII 
XXII 
XXII 
XXIII 

XXIV 
XXIII 
XXIII 


XXIV 
XXII 
XXIII 

xxin 


XXI 
XXIII 
XVIII 

XXI 

XXIII 
XXIII 


XXI 
XXIIt 
XXIII 


XXIV 
XXII 
XXIII 


XXIV 
XXIII 

XXIV 
XXIII 

XXIII 


Difference  in 

Altitude 

referred  to 

Intermeitiate 

Datura. 

Ic 

■t. 

+ 

1.7 

+ 

50.7 

+ 

42.3 

+ 

213.0 

+ 

287.0 

+ 

303.  0 

■1- 

620.0 

-t- 

2lil.O 

-t- 

206.  0 

+ 

032.  9 

+ 

278.2 

-1- 

0.8 

-t  1017.  5 

— 

361.1 

+ 

0.5 

-1-1037.7  1 

1- 

005.8 

+ 

2.6 

+ 

974.0 

+ 

621.0 

+ 

5.01.0 

+ 

3',7.8 

+ 

876.0 

+ 

72.6 

+ 

845.9 

Altitude 

above  the 

Lake  Shore 

Gauge  Zero 

Datum. 


1.7 

52.4 

94.7 

307.7 

594.7 

897.7 

307.7 
933.  7 
568.7 

94.7 
300.7 
933.6 
576.9 

6.8 
1024.  3 
0i;3.  2 

0.5 
1044.2 
672.  3 

2.6 
976  6 
623.  U 

52.  4 
803.  4 
971.  2 

94.7 
970.7 

52.4 
125.0 
970.9 


414  LAKE  BONNEVILLE. 

Table  XXIV. — lieduction  of  Results  to  the  Lake  Shore  Gauge  Zero  as  a  Common  Datum. — Continued. 


Point. 

Intermodi;ite  Diitutii. 

From 
Table 

Difference  in 

Altitude 

referred  to 

Intermediate 

Datum. 

Altitude 

above  the 

Lake  Stioro 

Gauge  Zero 

Datum. 

Liiko   SHifiice,    May,    1873.     Iiitcr|iolatLMl   from 
recorda  not  iucluded  iu  Taltli-  XXI. 

Feet. 

Feet. 

8.5 

IJouiic'villd  shore-Hue,  vicinity  of  Salt  Lalto  City. 
(2(1  determination.    Thirt   elevation  is  taken 

+  9C7.7 

970.2 

from  Vol.  Ill,  p.  92,  Report  of  Surveys  West  of 

lOOHi  Meridian). 

Lakf  surface,  July  12,  1877 

Lake  Shore  Gauge  Zero -  -  - 

XXI 

-1-      7.3 

7.3 

UouneviUe .shore-line,  vicinity  of  Black  Rock  ... 

Lake  surface,  July  12, 1877 

XXIII 

+  993.  U 

1000.3 

do 

XXIII 
XXIII 

-1-  633.  0 
+  247.0 

040.  3 
254.3 

."^tauHbury  Hhore-liue 

do 

Lake  Surface,  July  28, 1877;  interpolated    

Lake  Shore  Gaugi'  Zero  

XXI 

-t-       7.0 

7.0 

IIonnevillcaliorc-liUL',  uorlh  end  A«iiii  Uan;;e  (lat 

Lake  surface,  July  28,  1877 

XXIU 

+  1059.  0 

1000.  D 

deterniinatiiiu). 

I'rovo  .shore-line,  north  end  Aqui  Kan;;e  (lat  de- 
termination). 

do   

XXIII 

+  078.0 

085.0 

Lakoaiirfaco,  Nov.  25.  1880;  iulerpolatc'd 

Lake  Shoi-e  Gauge  Z-ro 

XXI 

+       1.7 

1.7 

Bonneville   shore-line,   north  enil  of   tlie  Aqut 

L:ike  surface,  Nov.  25,  1880 

XXIII 

•f  1058.  4 

1060.1 

Ran^xe  (2d  determination). 

Provo  shore-line,  north  end  .Vqui  K;iiinn  (2d  ths 

do 

XXIII 

+  076.9 

078.0 

termination). 

do 

XXIII 

XXIV 
XXII 

-1-  331.0 

332.7 

.52.4 
599.4 

Salt  Lake  City  Station  (0.  S.  R.  R.)  

Summit  (U.  S.  R.  R.),  vieiuitv  of  Point  of  the 

Salt  Lake  City  Station 

+  547.0 

Mount;iiii. 

Ronneville  sliore-liue,  vicinity  of  Point  of  Ihe 
Mount:un. 

U.S.  R.R.Summit 

XXIII 

+  358.0 

957.  4 

Provo  shore-line.  Point  of  the  Mouiit;iin   

Lake  surface,  Mcli-,  IH73.     luterpohiteil  from  ap- 

XXIII 

-  375.5 

581.9 
8.0 

proxiriiiito  d.ita  not  ineUnled  in  Table  XXI. 

Ronnevillo  shore  line,  vicinity  of  Stockton   

Lake  surnuw.Mch.,  1873    

XXIII 

+  1011.  u 

1019.0 

Provo  shore-lino,  vicinity  of  Stockton.^, 

XXIII 

XXIV 
XXII 

—  375.  0 

014.0 

52. 4 
82J.  4 

Salt  L:ike  City  Station  ( U.  S.  R.  R  ) 

Sautaquin  Summit  (0.S.R.R.)  

Salt  Lake  City  Station 

+  772,0 

Bonueville  shore-lino,  vicinity  of  Santaqniu 

Santaquin  Summit  (U.S.  R.  R.). 

XXIII 

+     7.5.0 

899.4 

Salt  Lake  City  Station  (U.S.  R.  R.) 

Salt  Lake  City  Station 

Lemiuglon  Station 

XXIV 
XXII 

.52.  4 
507.4 
89«.n 

-(-  4,55.0 
+  38G.B 

Bonneville  shore-lino,  vicinity  of  Lemiugton  — 

XXIII 

XXIV 

xxrii 

125.0 
137.5 

U.  S.  Signal  Service  barnmoter  at  Salt  Lake  City. 

Meridi;in  Monument 

+     12.5 

Fillmore  sub-base  barometer 

U".  S.  Sign;il  Service  barometer. 

XIX 

-H  823.7 

9C1.2 

Bonneville  shore-line,  vicinity  of  Fillmore 

Fillmore  sub-base  barometer  . . 

XXIII 

—    19.4 

941.8 

COMPUTATION  OF  HEIGHTS. 


415 


Table  XXIV. — ReducHon  of  liisulls  to  the  Lake  Shore  Gauge  Zero  as  a  Common  Datum — Continued. 


Poiut. 

Intermediate  Datum. 

From 
Table 

Difference  in 

Altitude 

i-eferred  to 

Intermediate 

Datum. 

Altitude 

above  tlie 

Lake  Slmre 

Gauge  Zeio 

Datum. 

Feet. 

Feet. 

XXIV 
XIX 

961.2 
893.  6 
564  5 

XXIII 

,')99    1 

butte. 

XXIV 
XIX 

901.2 
487.  1 

(Jainp  at  White  Muiiiituiii  Spniit; 

Fillmore  sub-base  barometer  . . 

—  474. 1 

Provo  shore-liue  uu  Wliiti_'  Mmititaiii  liiittc 

Camp  at  "White  Mountain 

XXIII 

+     08. 9 

556.  0 

Provo  tufa  deposit  on  Taberiiaclo  Butto  lava 

do 

XXIII 

+     42. 9 

530.0 

outflow. 

Filluiore  aub-ba.se  baiorneti-r 

XXIV 

901  2 

XIX 

—     17  3 

943.  9 

do 

XIX 

+       1.2 

963,4 

Bouueville  sboru-liue,  base  of  South  Twiu  Peak 

do 

XIX 

—    32.5 

928.7 

Salt  Lake  City  Station  (U.  S.  K.  R.) 

Mil  fold  Station.  U.S.  li.  11.  extension    

xxrv 

52.4 

Salt,  Lake  City  Station 

,XX1I 

+  707.5 

759.9 

Bonneville  ahore-lino,  vicinity  of  Milford  (lat  de- 

Milfoid Station    

XXIII 

+  l.i2.7 

912,0 

termination). 

Fillmore  sub-base  barometer 

Canipuu  Boaver  River,  vicinity  of  Milford 

Filliiioru  8ul)-baao  baronietor  - 

XXIV 
XIX 

961,2 
742.6 

—  218.  6 

Camp  (in  Boaver  River 

Milford  Station 

XXIII 
XXIII 

+      7.6 
+   152.  7 

Bonuevillo  ahoru-line.  vicinity  of  Milfonl  C-d  i\v 

902.  9 

termination). 

XXIV 

961.2 
885.2 

Bonneville  shore-line,  vicinity  of  Milford  (lid  de- 

Killiiioi-o snb  baae  barometer- . 

XIX 

—    76. 0 

termination). 

Fillmore  sub-base  barometer 

Bonneville  shore-line,  7  niilea  south  of  Milfurd 

XXIV 
XIX 

-     961.2 
912.3 

Fillmore  sub-base  barometer. . 

-    48.9 

Bnnnevillf  sliore-line,  2  miles  oast  of  Thermos 

do 

XIX 

—    76.6 

884.6 

Bonmnille  shoredine.  4  miles  south  of  Thermos 

do 

XIX 

—    48.7 

9!2.  5 

Bonneville  shore-line.  7  miles  south  of  'i'licrmo.s 

...  do... 

XIX 

—    43.1 

!I19, 1 

Bonneville  sbore-linr,   1  mile  west  of  Antelope 

do 

XIX 

+    :i8.7 

999,9 

Spring. 

Bonneville  shon*-Iine  at  Sulphur  Sprinjis. 

do 

XIX 

+     4.5.  2 

1000,4 

Bonneville  shoredine,  west  of  entrauee  to  Pinto 

do 

XIX 

1    214,1 

117.5,3 

Canyon. 

Bonneville  ahore-line,  oaatof  entrance  to  Meadow 

do 

XIX 

+  296.6 

1257. 8 

Creek  Canyon. 

Bonneville  shore-line,  west  of  entrance  to  Mea<lo w 
Creek  Canyon. 

.  do     

XIX 

+   291.5 

1255.7 

Bonneville  shore-lino,  north  of  entrance  to  Shoal 
Creek  Canyon. 

do 

XIX 

+  265.8 

1227.0 

416  LAKE  BOISNEVILLE. 


ALTITUDES   OF  SHORE-LINES   AND  THEIR  DIFFERENCES. 

For  cotivenieuce  iu  com  par  son,  all  tlie  detcriniiied  altitudes  of  points  on  the 
Bonneville  shoreline  have  been  collected  in  Table  XXV  and  arraiif;ed  with  reference 
lo  latitude,  befjiiininfv  with  the  most  nortiierl.v.  In  addition  to  this  a  column  lias 
been  i)repared  S'^'inR  tl^e  "Inferred  high-water  level"  of  the  Bonneville  stage,  with 
its  jjrobable  error.  The  preparation  of  this  column  involves  several  considerations. 
In  tiie  tirst  i)lace,  the  shore  record  to  which  levels  were  run  consistetl  in  each  case  of 
a  topographic  feature  which  might  or  might  not  stand  at  the  precise  level  of  the  cor- 
responding water  surface.  In  some  cases  there  was  reason  to  l)elieve  that  it  was 
hialier,  in  other  cases  that  it  was  lower,  and  in  order  to  obtain  the  altitude  given  in 
the  right-hand  column,  a  correction  was  applied.  To  obtain  the  value  of  the  probable 
error  of  this  altitude,  two  sources  of  error  had  to  be  considered,  the  eiror  of  instru- 
mentation, or  error  of  the  leveling  i)roper,  and  the  error  of  the  estimated  correction 
to  the  measured  height. 

In  deciding  upon  the  amount  of  allowance  or  correction  to  be  applied  to  the 
determined  altitudes  in  order  to  obtain  the  iufeired  high-water  line,  much  attention 
was  given  to  the  local  characteristics  of  the  shore  line  in  the  vicinity  of  each  deter- 
mined point.  The  effect  of  local  conditions  was  the  subject  of  sjjecial  study  by  Mi'. 
Gilbert,  and  the  allowance  for  difference  in  altitude  between  the  shore  feature  meas- 
ured and  the  corresponding  water  surface  was  in  each  case  based  on  his  estiiiuite.' 

With  I'eference  to  the  error  of  instrumentation,  the  attempt  was  made  to  deter 
mine  the  general  precision  of  each  hypsometric  method  used.  A  probable  error  in 
accord  with  such  determined  precision  was  assigned  to  eacih  separate  measnremenf, 
and  the  probable  error  of  each  measured  altitude  was  deduced  from  the  combination 
of  the  errors  of  the  several  steps  on  which  the  measurement  was  based. 

The  probable  error  ef  the  estimated  allowance  for  the  difference  in  altitude 
between  the  topographic  feature  measured  and  the  high  water  level  was  itself  a  mat- 
ter of  estimate  oidy,  being  based  upon  considerations  arising  from  Mr.  (Jilbert's  gen- 
eral study  of  the  subject. 

The  probable  error  of  the  collected  altitude  was  deduced  by  combining,  in  the 
usual  manner,  the  probable  erior  of  instrumentation  with  the  jjrobable  error  of  the 
"estimated  allowane(>." 

In  ascertaining  the  precision  of  the  bar(unetric  work,  use  was  niaile  of  the  long 
series  of  simultaneous  observations  at  Fillmore  and  Salt  Lake  City.  Sixty  indei)end- 
ent  comi)ntations  were  made  of  the  difference  in  altitude  of  the  two  stations,  each 
computation  being  based  on  a  single  set  of  concurrent  observations.  A  computation 
based  on  the  discrrepancies  of  the  sixty  results  showed  the  luoliable  error  of  a  single 
determination  to  be  IrliS  feet.  The  errors  assigned  to  the  barometric  determinations 
were  estimated  on  this  basis,  allowance  being  made  for  distance  and  other  special  con- 
ditions. 

A  part  of  the  leveling  work  was  dui)licated,  and  an  examination  of  the  records 
of  such  duplicated  work  led  to  the  belief  that,  as  executed  by  u.s,  a  line  of  levels  not 
exceeding  five  miles  in  length  nor  1000  feet  in  vertical  range,  need  not  be  assigned  a 


'A  (lisi^Mssiou  of  this  siilijiTt  will   ho  fouiiil   in  Cliaiilcr  III  of  tliis  volume,  iinJer  the  ht'a<]iii<;s 
"  EmbaukiniMit  Series"  aud  "  Doteniiiiiatiou  of  Still-water  Level,"  i)p.  Ul-l'i').     G.  K.  G. 


HEIGHTS  OF  SOORE-LIXES. 


417 


greater  probable  error  than  one  foot.  Locke's  liaml  level,  when  supported  by  a  staff 
and  used  on  a  steep  hillside,  was  found  to  have  a  probable  error  of  about  one  foot  in 
SOO  feet  of  ascent. 

The  probable  errors  recorded  in  the  following  tables  were  obtained  by  combining 
the  estimated  probable  errors  of  measurement  with  the  estimated  probable  errors  of 
identification  of  the  plane  of  tlie  ancient  water  surface.  It  is  recognized  that  any 
individual  determination,  not  duplicated,  msiy  involve  some  gross  error  for  which  no 
allowance  is  made,  but  if  such  errors  exist  their  number  is  small. 

Tablk.  XW.—Coniptiralive  Schedule  of  Jltit  tides  of  Poiiils  on  the  Boiinerille  Shoreline. 


Locality. 

Description  of  Determined  Point. 

Di'terniint'd 
Alliliulii 
almve  Iho 

Lake  Shore 
Gau;lo  ZiTo. 

Iiiferreil 
hiyli-water 
level,  above 
Lake  Shore 
Gauge  Zero. 

Feet. 

Feet. 

Red  Kock  Pasa 

Inner  edge  of  a  cut-terrnco 

897.7 

906  ±  4 

....  do 

933.7 
933. 0 

940+  3 
942+  4 

....  do 

Kelton  Butte 

Crest  of  an  enibnukmont  

1024.  3 

1019+   3 

1014.2 

1050+   3 

AVniard. 

do 

976.  G 

985+   3 

971.1 

981  ±  5 

970.7 
970.9 

980  ±  5 
979+  5 

Salt  Lake  Citv            

Dous^laa.     By  first  determination. 

S-ilt,  LaVe  Citv 

Inner  edge  of  a  ctit-tprrace  back  of  Fort 
Douglas.    By  .second  determination. 

970.2 

984+  5 

I'Uick  Kock ■ 

TiHier  fdge  of  a  cnt-toTrncu 

1000. 3 

1008+  3 

North  ci.d  of  Aijiii  Uauj^e.. 

Inner  edgeof  cut  terrace.     By  first  determi 
nation. 

1000.  1 

1068  i  3 

Nintli  end  of  Aqiii  UaiiL^o. . 

Innei"  edge  of  a  «ut-ti*rr;n-n.     By  second  ilt^- 
tonnination. 

lOOG.  0 

1074+  4 

I'oiutof  the  Mmiiilain  .   .. 

957.  4 
1019.0 
899.4 
894.  0 
911.  S 
893.  G 
943.9 
902.  4 

9)0+   3 
1014+  5 
902+   3 
902+  5 
938+   8 
902  i  15 
953  +  15 
971+20 

do 

do    

Pavaiit  Butte   

Near  outer  edge  of  a  cut-terrace 

Middle  of  a  cut-torrace , 

Outer  edge  of  a  out-terrace 

B;ise  of  North  Twin  Peak. . 

Base  of  South  Twin  Peak.. 

..       do. 

928.  7 

939+20 

Milford    ... 

End  of  a  V-embanknient.     The  elevation 
given  in  the  third  columu  is  the  general 

900.  3 

904  +  10 

mean  of  the  three  determinations  of  the 

point  given  in  Table  XXIV,  weighting 

the  first  at  5,  the  second  at  ■'J.  and  the 

third  at  1. 

7  miles  aouth  of  Milford  ... 

Outer  edge  of  a  cnt-terraco 

912.  3 

921  +  ''O 

2  miles  east  of  Thermo=» 

Middle  of  a  narrow  cut-terrace 

884.6 

893+25 

4  miles  aouth  of  Tliernibs  . 
7  miles  south  of  Thermoa 

Middle  of  a  cut-terrace 

912.5 
919.1 

921  ±25 
927+25 

do 



MON   I- 


-27 


418 


LAKE  BONNEVILLE. 


Tablk  XXV.— Comparative  Schedule  of  Altitudes  of  Points  on  the  Bonn.eville  Shore-line — Contiuued. 


Locality. 

Description  of  Determined  Point. 

Det<-ruiincd 
Altitude 
aliove  the 

Lake  Shore 
<iauj;e  Zero. 

Inferred 
liigh-waier 
level,  almve 
Lake  Shore 
Gauge  Zero. 

.Viitf'Iopo    Sprinj:    (Lower 
Escalantf  Desert). 

Middle  of  a  cut-terrace   

Feet. 
999.9 

1006.4 
1175.4 

12.';7.  8 

1255.7 
1227,0 

Feet. 
1008  ±30 

1015  ±25 
1175  ±35 
1258  ±35 

1256  ±35 

1227  ±35 

Outer  edjje  of  a  narrow  cut-terrace 

Outer  edge  of  a  delta  t  erraco 

Pinto  Canyon 

Meadow    Creek    Canyon 

(East  of  entrance). 
Meadow    Creels    Canyon 

(West  of  entrance). 
SlioalCreeli  Canyon  (North 

of  entrance). 

Outer  edge  of  a  delta  terrace    

Outer  edge  of  a  delta  terrace 

Tables  XXVI  and  XXVII  jiresent,  in  form  similar  to  the  arrangement  ot  Table 
XXV,  the  deteruiinatious  made  ou  the  Provo  and  St.insbury  shorelines. 

Table  XXVI. — Comparative  Schedule  of  Allitiides  of  /"oin/.s  oii  the  Provo  Shoreliiie. 


Locality. 

Description  of  Determined  Point. 

Altitude 

.above  Lake 

Shore  Gauge 

Zero. 

Inferred 

water  level, 

above  Lake 

Shore  Gauge 

Zero. 

Toner  edge  of  a  cut-terrace 

Crest  of  a  bar  ou  ed"e  of  a  della    

Feet. 
568.7 
576.9 
663.2 
672.3 
623.  6 
040.  3 
678.0 

685.0 

581.9 
644.0 
5fi4.5 
556.0 
530.0 

Fed. 
569  ±  3 
577  ±  2 
663  ±    3 
672  ±  a 
024  ±  5 
6t0±  4 
679  ±  3 

685  ±  4 

580±  3 
640±  5 

553  ±10 
530  ±15 

Logan 

Inner  edge  of  a  eut-tt-rrace 

do 

Willard 

do 

do    

North  endof  the  Aijui  Range 
Northendof  the  A(]ui  liange 
Point  of  the  Mountain 

Inner  edge  of  a  cut-terrace,  by  first  determi- 
nation. 

Inner  edge  of  a  cut-terrace,  by  second  de- 
termination. 

Croitofabar 

Inner  GiXge  of  a  ciit-terrace — indistinct 

Crest  of  uu  enibankment 

White  Mountain  Spring 

Do 

Line  of  calcareous  tufa  on  lavaoutllow  about 
Tabernacle  Butte. 

Tablk  XXVll.  —Comparatire  Schedule  of  Jltiliides  of  Pointii  on  the  Stiinshury  Shore-line. 


Black  Roek Cut-terraco. 

North  end  of  the  A  qui  Range. 


254.  3 
332.7 


254  ±3 
333  ±3 


FIEIGHTS  OF  SHOEE-LmES. 


419 


Tables  XXVIII  and  XXIX  are  in  general  compiled  directly  from  Tables  XXV, 
XXVI  and  XXVJI,  and  give  tbe  diflereuces  in  altitude  of  tlie  higb-water  lines  of  the 
liinineville  and  Provo  stages,  and  Prove  and  Stausbnry  stages  respectively.  The 
Siiowsville,  Dove  Creek,  and  Matlin  results  come  direct  from  Table  XVIIl. 

Table  XXVIII. —  Diffen iivtn  in  Alliliidc  of  the  IloniicriUe  and  Provo  Sliorc-lim.'i  nl  furious  Localitiex. 


Locality. 

Description  of  Point  on  Bonne- 
ville Shore. 

Description  of  Point  on  Prove 
Shore. 

Ditference 
of  Altitude. 

Outor  edj;e  of  a  cut-terrace  . 

Inner  edge  of  a  cut-terraco  .   . . 
do 

Outer  edge  of  a  cul  terrace 

Inner  edge  of  a  cut-terraco 

Cre.st  of  bar  on  edge  of  a  delta 
terrace. 

Crest  of  an  embankment  - 

Inner  edge  of  a  cut-terraco 

....  do    

Feet. 
365+  2 
371+  2 
305+  3 

382+   2 
356+  3 
374+  3 
413+   2 
411+   3 
301+   3 
300+   3 
389+   3 
380+   3 
374+   3 
370  t    3 
392  .^:   3 
397+  2 
382+  5 
339  +  10 
385+  8 

345+  2 
341+  2 

Fiankliu 

WcU^viUc             

Crest  of  an  embankment    

do     

Kclton 

rroinontorv 

Inner  edge  of  a  cut-terrace 

Crest  of  a  bar 

Outer  edge  of  a  cut-terrace 

Inner  edge  of  a  cut-terrace 

do 

Matliu     

Crest  of  a  bar 

Willani                       

Inner  edge  of  a  cut-terrace 

do 

North  end  Aqui  Range - 
Grantsvillo 

...  do          

.do 

Cre.st  of  an  embankment  ...   . . 
....  do      

..do    .              

Point  of  the  Mountain . 

..    do      -.                    .... 

Crest  of  an  embankment  

Inner  edge  of  a  cut.terrace 

Crest  of  an  embankment 

Outer  edge  of  a  cut-terrace 

Cut-terrace  (indefinite) 

Crest  of  embankment  on  White 
Mountain  Butte- 

Crest  of  an  embankment  

do 

do                

do 

Fish  Spring  , 

Outer  edge  of  a  cut-terrace 

Crest  of  a  hav  bar 

Crest  of  an  embankment  ...   . 

do      

Preuss  Valley 

(Middle  series) 

(South  series) 

Table  XXIX. — Differences  in  Altitude  of  the  Provo  and  Stansbury  Sliore-lines  at  various  localities. 


Vicinity  of 

Nature  of  the  Provo  Shore. 

Nature  of  the  .Stansbury 
Shore. 

Piiference 
nf  Altitude. 

Outer  edge  of  a  cut-terrace    -. 
Inner  edge  r'f  a  cut-terrace  - .  - 
do    

Feet. 
310  ±3 
380  (?) 
346 1 3 

Black  Rock 

North  end  of  tbe  Aqui  Range 

APPENDIX   B. 

ON  THE  DEFOKMATION  OF  THE  GEOID  BY  THE  REMOVAL,  THROUGH 
EVAPORATION,  OF  THE  WATER  OF  LAKE  BONNEVILLE. 


By  R.  S.  Woodward. 


The  following  paragraphs  contain  an  outline,  with  special  reference  to  the  Lake 
Bonneville  problem,  of  a  general  investigation  of  the  form  of  the  geoid  as  inlhienced 
by  local  attracting  masses  of  certain  determinate  forms.  The  fullest  publication  con- 
stitutes Bulletin  No.  48  of  the  U.  S.  Geological  Survey,  entitled  On  the  Form  and 
Position  of  the  Sea-Level.  Some  of  the  mathematical  work  appears  in  the  Annals  of 
Mathematics,  in  Nos.  5  and  6  of  Vol.  12  and  No.  I  of  Vol.3;  and  the  principnl  numer- 
ical results  with  reference  to  an  ice  cap  are  abstracted  in  the  paper  by  Messrs.  Cham- 
berlin  and  Salisbury  on  The  Drifcless  Area  of  the  Upper  Mississippi  Valley,  in  the 
Sixth  Annual  report  of  the  U.  S.  Geological  Survey,  pages  291-298. 

The  form  and  position  assumed  by  the  surface  of  the  ocean  or  the  surface  of  a 
lake  at  any  time  are  determined  by  the  contemporaneous  distribution  and  velocity  of 
rotation  of  the  earth's  mass.  Any  change  in  that  distribution  or  in  that  velocity  of 
rotation  ius'olves,  in  general,  changes  in  both  the  form  ami  position  of  the  free  surfaces 
of  all  terrestrial  bodies  of  water.  Such  surfaces  are  called  level  surfaces,  or  now  more 
commonly,  equipotential  surfaces.  Mathematically  they  are  always  regarded  as  closed 
surfaces,  or  as  encompassing  the  earth,  however  limited  their  visii)le  i)ortions  i)re- 
sented  by  isolated  bodies  of  water  may  be.  Thus,  the  sea  surface  is  imagined  to 
extend  through  the  continents,  its  position  at  any  invisible  point  being  the  height  to 
which  water  would  rise  if  permitted  to  flow  through  a  canal  from  the  sea  to  that 
point. 

Of  the  two  factors  which  determine  the  form  and  position  of  the  sea  level  at  any 
epoch,  the  distribution  of  the  earth's  mass  is  the  more  important.  Indeed,  the  rota- 
tion of  the  earth  may  be  entirely  ignored  in  computing  the  eflects  on  the  sea-lev<^l  of 
such  changes  in  the  su[)erficial  distribution  of  matter  as  are  here  considered. 

It  will  be  convenient  in  what  follows  to  distinguish  between  the  relative  atti- 
tudes of  the  surfaces  of  the  sea  or  any  similar  equipotential  surfaces  at  different 
epochs  by  referring  to  them  as  disturbed  and  undistiubed  surfaces.  Thus,  according 
as  we  call  the  present  sea  surface  uudisturbud  or  disturbed  the  past  and  future  sur- 
faces are  disturbed  or  undisturbed.  It  will  also  be  convenient  to  call  any  mass  pro- 
ducing such  relative  changes  in  sea  level  a  disturbing  mass. 

421 


422  LAKE  BONNEVILLE. 

In  the  paper  referred  to  above  it  is  sbowii  that  tlie  efifect  of  superficial  masses 
of  small  maguitudo  in  comparison  with  the  earth's  mass  iu  distorting  the  sealevel  is 
expressed  by  the  formula 

«  =  — ^— ,  (I) 

in  which  v  is  the  elevation  or  depression  of  the  disturbed  surface  with  respect  to  the 
undisturbed  at  the  point  where  the  potential  of  the  disturbing  mass  is  V;'  V„  is  the 
potential  of  the  disturbing  mass  along  the  line  of  intersection  of  the  disturbed  and 
undisturbed  surfaces,  or  the  value  of  V  where  i'=:0;  and  g  is  the  acceleration  of 
gravity. 

The  application  of  the  above  formula  presents  lu)  <lif6culty  except  in  the  calcu- 
lation of  the  potentials  V  and  Vo,  which  are  in  some  cases  quUe  complex  quantities. 
For  one  of  the  most  important  classes  of  cases,  namely  that  in  which  the  disturbing 
mass  is  symmetrically  disposed  about  a  radius  of  the  earth's  surface,  the  ])0tentials 
have  been  expressed  in  terms  of  integrals  which  may  be  readily  evaluated  for  the 
characteristic  points  of  the  disturbed  surface.  In  this  class  of  cases  the  disturbed 
surface  will  evidently  be  equi  symuietrical  with  respect  to  the  axis  of  the  disturbing 
mass,  and,  disregarding  the  etfect  of  the  rearranged  water,  the  auiount  of  the  disturb- 
ance is  defined  by  the  following  formula : 


V 


=  4-Jo     -^-~,^-"'^V(W.  (2) 


Herein  r  has  the  same  meaning  as  in  ( 1 ),  p  is  the  density  of  the  disturbing  mass,  p„.  the 
mean  density  of  the  earth,  tt  the  number  3.14159  +,  ft  the  angular  distance  of  any 
point  of  the  disturbing  mass  from  its  axis,  and  fto  is  the  angular  radius  of  the  border 
of  the  mass  or  the  limiting  value  of  /?.  The  quantity  I  is  a  definite  integral  which 
may  be  most  briefly  expressed  thus — 


r"  /cos  p 

J  0     V  cos  p  ■ 


COS  ft  \i 

—  ]  dp  when  (x<ft 


cos 

(3) 


/■'     /cos  H  —  COS  /i  \2  ,  ,  ^      , 

=    I       ( (In  when  a>ft, 

,  /  0     V^'os  2>  —  cos  a  I     ^  '  ' 


wherein  a  is  the  angular  distancie  of  anj-  ])oint  of  the  disturbed  surface  frotn  the  axis 
of  the  disturbing  mass,  a  and  v  are  thus  polar  coordinates  of  the  disturbed  sea 
surface. 

The  effect  of  the  rearranged  sea-water,  ignored  above,  is  simply  to  produce  an 
exaggeration  of  the  type  of  surface  defined  by  (2),  ami  this  exaggeration  may  be 
expressed  by  a  series  of  rapidly  converging  terms  (see  §§  20-24  of  paper  on  Form  and 


'If  Hi  be  an  element  of  the  (U.stiul)iiig  mass  aiiil  r  its  dislaiice  tVoiu  the  point  in  question,  thi; 

potential  of  the  mass  is  the  sum  of  all  I  lie  iinotieuts  '",  or  V  ^  3  '"  .     The  non  mathematical  reader 

)•  r 

shonld   distinguish  carefully  between   potential   and  attraction,   the  latter  bcini;  a  dirivative  of  the 

former. 


DEFORMATION  OF  GEOID. 


423 


Position  of  the  Sea  Level),  but  for  tbo  small  masses  bere  considered  tbe  snm  of  these 
additional  terms  is  iiisigiiiflcant.  In  all  cases,  indeed,  tbe  characteristic  effects  are 
expressed  by  equation  (13). 

For  lenticular  masses  of  tbe  type  assumed  iu  the  text,  the  thickness  is  given  by 
the  expression 


<p{ft) 


0 


sin'^i^X 
sin"  yjoj' 


(3) 


Here  ho  is  tbo  thickness  along  the  axis  of  the 
mass,  /3  and  fto  have  tbe  meanings  assigned  ^ 
above  and  h  is  any  positive  integer.  This  for- 
mula makes  (p{/i)  =/'oi  or  tbe  mass  of  uniform 
thickness  when  n  is  iufiuite.  For  other  values 
of  n  tbe  mass  will  be  thickest  along  its  axis 
and  diminish  in  thickness  more  or  less  rapidly 
as  we  pass  from  tbe  axis  to  tbe  border,  or  as  /i 
increases  from  0  to  ft,,.  Some  of  tbe  curves  de- 
fined by  ('^)  are  shown  in  Figure  51.  Tiie  scale 
for  the  sector  ABC,  representing  a  great  circle 
of  tbe  earth  through  tbe  axis  of  a  lenticular 
lake  basin,  is  1:125,000,000  and  the  radial 
scale  for  tbe  curves  ?i  =  1,  3,  7  is  exaggerated 
about  5,000  times,  the  assumed  value  of  /(„  being 
1,000  feet. 

For  the  particular  value  of  (p{ft)  given 
by  (3),  equation  (2)  becomes 


v  =  3 


.A 


Fin.   51.— Crosa-sectiou   of  Ideal    Lc-nticuhir  Lake 
Basins. 
Scale  for  section  of  terrestrial  spliote  i^^ninson- 
Rndicul  scale  for  thickness  of  disturbing  mass,  or 


«(^)  = 


\  sm"  Jflu/ 


1000  feet. 


7rp„ 


r'  \y^m  ift\'>        nn  \ 


(4) 


If  we  represent  the  values  of  the  definite  integral  in  tiiis  equation  for  points  along 
tbe  border  and  at  the  center  of  the  mass  by  S2  and  Si  respectively  and  denote  tbe 
corresponding  values  of  v  by  V2  and  »i  respectively,  we  find 


ih 


hop 


{  S2  -  S,  } 


(5) 


This  expresses  tbe  difference  in  altitude  of  tbe  disturbed  surface  at  tbe  center  and  at 
tbe  border  of  the  disturbing  mass.  When,  as  in  the  present  case,  tbe  disturbing  mass 
is  water  in  a  lake  basin,  we  must  substitute  for  /j  tbe  difference  in  density  of  water 
and  superficial  rocks.     That  is, 

p  =  1  —  2.8  =  —  1.8  approximately. 

Finally,  if  we  wish  to  ascenain  tbe  seiiaration  at  tbe  center  of  tbe  basin,  due  to 
a  change  in  the  density  of  its  contents,  of  eipiipotential  surfaces  which  intersect  along 


424 


LAKE  BONNEVILLE. 


the  border,  we  have  only  to  diflerentiate  (5)  refjarding  (i'2— »i)  and  p  as  variables  and 
substitute  for  Zip  the  change  in  density  of  Mie  contents  of  the  basin.  Thus,  the  sepa- 
ration is  expressed  by 

Tlie  vaUies  of  S|  and  S2  in  (•^)  and  (G)  may  lie  found  from  the  following  oxpres- 

n 

b,  =  ^^  _^  J  n  sin  ^/i„. 

S.  =  ^  sin  hft„  \  .,  (~_^j  +  jy  (,^  ^^^  (1  +  sin^  }Ji,) 

+ \ 


Rions 


The  march  of  the  above  functions  Si  and  Sj  and  the  corresponding  values  of 
(v.,  —  ?'i)  and  J  (i'2  —  lu)  is  illus-trated  by  the  numerical  results  given  in  the  table  below. 
The  data  for  these  results  are  the  foUowiu"  : 


1000  feet,     /y„  =  arc  of  1", 

r,  r. 


IJ     =~  LS', 
zJp  =  -I. 

The  results  in  the  fifth  column  show  how  niucli  nearer  to  the  center  of  the  earth  the 
assumed  lake  surface  is  at  the  middle  of  the  basin  than  at  its  border;  and  the  results 
in  the  sixth  column  show  how  much  ashore  trace  at  tlie  middle  of  the  basin  would  be 
found  to  be  above  the  contemporaneous  trace  at  the  border,  by  a  line  of  spirit  levels 
run  after  the  removal  of  the  water. 

TaBlk  XXX. —  Valncs  skoiriiiy  relative posUlnna  of  Lend  Surfaces  in  a  lake  hasiii  140  miles  in  diameter  and 

of  1000  feet  maximnm  (axial)  depth. 


n 

s, 

Sj 

s,-s, 

1),  — t), 

^(i>2  — »,) 

FMt. 

Feet. 

1 

n. 00436 

O.OOICI 

0.  00^75 

2.70 

1.  .-,0 

2 

.  0D.)82 

.00:.'45 

.  00337 

3.31 

1.84 

3 

.  00034 

.  002DS 

.  OOJ50 

3.  50 

1.94 

4 

.  OU0U.S 

. 00333 

.  00365 

3.  58 

1  99 

0 

.  011727 

.  00359 

.  00368 

3.01 

2.01 

G 

.  00748 

.  00379 

.  0036!) 

3.62 

2.  01 

7 

.  00761 

.  00395 

.  00160 

3.62 

2.01 

8 

. 00776 

.00407 

.  00369 

3.02 

2  01 

9 

.007^(0 

.00418 

.  003(18 

3.  Gl 

2.01 

10 

.00793 

. U0427 

. 00366 

3.  .59 

1.69 

00 

.  00(173 

.  0U5S6 

.  00317 

3.11 

1.73 

ATPENDIX   C. 

ON  THE  ELEVATION  OF    THE    SUEFAOE  OF  THE    BONNEVILLE  BASIN 
BY  EXl'ANSION  DCE  TO  CHANGE  OF  CLIMATE. 


By  E.  S.  Woodward. 


The  folIowiDg  problems  were  submitte<l  to  me  by  Mr.  Gilbert: 

(1)  Ten  lliiiusaiid  years  aj;i)  tlio  Kiiifacc,  (mean)  teiiiperatiire  of  the  Boiiiievillo  basil),  wliieli  had 
been  long  ^'onstanf,  was  raised  10  F.  and  it  Las  been  sinee  nncbanjied.  The  linear  exiiansiiin  of  the 
subjacent  material  is  .000,1101!  perdei;ree  F. ;  tbe  cnbic  expansion  .000,018.  Horizontal  dilatation  bein" 
prevented  l>y  interference,  tbe  total  eiil)ic  expansion  was  expressed  in  vertical  dilatation.  How  many 
leet  was  tbe  surface  of  the  groniul  lifted  ? 

(2)  Same  as  above  for  period  of  100,000  years. 

(3)  Same  as  above  for  period  of  l,00O,00u  years. 

The  cooling  by  coiuliiotion  of  a  large  s[)liere  like  the  earth  from  an  initial  uiii- 
(brm  temperature,  gives  rise  to  cubictil  contraction  whose  amount  is  assigned  approxi- 
mately by  the  following  formula:' 


V    71 


zlV  =  Syrrhiea  ^1  - 
in  which 

r  =  the  radius  of  the  sphere, 

u  z=  the  initial  unitbrin  e.Kces.s  in  temperature  of  the  sphere  over  that  of  the  sur- 
rounding medium, 
a^  =  the  coelidcient  of  diffusion,  assumed  constant  for  the  whole  sphere, 
e  =  tbe  coetiticient  of  cubical  contraction,  assumed  constant, 
t  =  the  titne  after  tlie  initial  epoch, 
;r  =  3.1415+. 

This  formula  will  apply  to  the  earth  for  l,0()(),()O0,()0l»  years  subsequent  to  the 
initial  epoch  witliout  iiitioducing  errors  greater  than  those  involved  in  the  assump- 
tion of  constancy  of  a  and  e. 

Conversely,  the  above  formula  will  give  the  cubical  expansion  of  a  sphere,  con 
sequent  upon  being  immer.sed  in  a  medium  which  maintains  a  constant  surface  tem- 
perature u  degrees  higher  than  tlie  initial  temperature  of  the  sphere. 

'  Forcorapleto  formula  see  Aunals  of  Mathematics  Vol.  Ill,  No.  5. 

425 


426 


LAKE  BONNEVILLE. 


If  in  the  latter  case  wc  suppose  tbe  total  volumetric  expansion  to  result  in  ver- 
tical uplift,  an  eflcct  wliicli  would  follow  from  heating  the  earth's  crust  if  it  behaved 
under  expansion  like  a  liquid,  the  amount  of  the  uplift  will  be  expressed  very  closely 
by  the  quotient  of  equation  (1)  divided  by  the  area  of  the  surface  of  the  sphere.  Thus, 
calling  the  amount  of  the  uplift  z/r,  we  have 


STir^uea 


Ar  = 


n 


inr^ 


=  2uea 


il- 


(2) 


tJsing  the  year  and  the  British  foot  as  units,  Sir  W.  Thomson  finds  a  =  20. 
With  this  value  and  with  u  =  10°  F.  and  c  =  0.000018,  (2)  becomes 

Foot. 

zJr=z  0.00406  V  7. 
This  gives  the  following  values  of  Ar  corresponding  to  several  values  of  <: 


1. 

^r. 

Tears. 

10,  000 

100,  000 

1,000,000 

Feet. 
0.41 
1.28 
4.00 

INDEX. 


Page. 

Aa  at  Ice  Spring 323 

Adams,  J.,  lake  rampirts 71 

Adolescent  coast  lines. *53 

Airy,  G.  B.,  tbeory  of  waves 26,29 

Alg» 259 

Allen,  O.  r>.,  analyses  of  Bonneville  earths 200 

analyses  of  Sevier  Lake  desiccation  products. . .  226 

analysis  of  water  of  Great  Salt  Lake 253 

Alluvial  cone  and  fault  scarps,  view 349 

Alluvial  cones,  Bonneville  Basm 91 

Frisco  Kango 92 

Marsh  Creek ■-  HB 

Lake  Creek 185 

aridity  and  220 

Alluvial  fans 81 

Alluvial  terraces  and  fault  scarps,  Kock  Canyon 344 

American  Fork 346 

near  Salt  Lake  City 349 

East  Canyon 352 

Alluvial  cone  terrace 81 

Altitudes  and  their  determination 405 

Altitudes  of  shore-lines 362,427 

American  Fork,  deltas 155,  346 

fault  scarps 346 

Analyses,  tufa 168 

White  Marl  and  Yellow  Clay 201 

waters  of  City  Creek,  BearKiver,  and  L'tah  Lake  207 

Sevier  Lake  briue  and  desiccation  products 226 

water  of  Great  Salt  Lake 252 

waters  of  Bear  River  and  Utah  Lake 254 

Andrews.  Edmund,  theory  of  littoral  transportation .  26, 41 

subaqueous  rid;;e3 44 

Antelope  I-land  bar 240,  243,  410 

Appalachian  Valley 391 

Arpii  Range,  fault  structure 341 

fault  scarps  352 

heights  of  shoredines 366,370,372 

measurement  of  shore  lines 412,  414,  417,  418,  419 

Area,  Great  Basin 5 

Bonneville  Basin 20 

Lake  Bonneville  at  highest  stage  105 

Lake  Bonneville  at  Prove  stage 134 

Sevier  Lake  2i5 

Areas,  interior  basins  of  Arizona,  New  Mexico,  and 

Texas li 

various  lakes 106 

Great  Salt  Lake 243,244 

Aridity  and  alluvial  cones 220 

Aridity  of  Great  Basin,  described 6 

cause 10,  280 


Page. 

Arizona,  interior  basins  11 

Pleistocene  eruptions    337 

earthquake 361 

Arno  Valley,  Pliccene  fauna 399,400 

Arrow  point,  fossil 303 

Artemia  gracilis 258 

Barometric  measurement  of  shore  lines 363,406 

Barometric  measurements,  probable  errors  416 

Barrier,  described 40 

compared  with  other  ridges 87 

Bairy,W.C.,  tbeory  of  salt  harvest 224 

Bars.     (See  alao  Bay  bars)    48 

Basalt  Valley 219 

Basaltic  eruptions,  Bonneville  Basin 319,  325, 338 

map - 334 

Basin  Ranges,  type  of  at ructuro 5 

of  the  Bonneville  Basin 91 

Basins,  hydrogr-iphic 2 

interior,  of  Aiizona,  New  Mexico,  and  Texas...  11 

of  the  Bonneville  Basin 122,222 

Basaett,  H.,  analysis  of  water  of  Great  Salt  Lake 251,  253 

Bay  bars,  origin  and  character   48 

Snake  Valley 111,112 

Tooele  Valley , 131,132 

Beach,  origin 39 

profile. 39,42,45 

Bear  River,  deposits  in  Cache  Valley. 163 

gate  of ITS 

possible  changes 218, 263 

irrigation  250 

Bear  River  water,  precipitation  experiments 206 

analysis 207,254 

Beaumont,  Elie  de,  shore  topography 26 

limitation  of  tidal  action    29 

variation  of  beach  profile 42 

Beaver,  fossil  303,394,400 

Beaver  Creek  delta 166 

Becker,  G.  F.,  cited 284 

Beckwith,  E.  G.,  cited 14 

Bellville  Creek  delta 162 

Bench-mark  at  Black  Rock,  installation 231, 409 

leveling 232 

height 233,410 

map -. 390 

Benchmark  at  Farmington 409 

Biinadou,  J.  B 18 

Big  Cottonwood  Creek  delta 165 

Big  Willow  Creek  moraines  309 

Bipartition  of  lacustrine  and  glacial  epochs 270 

427 


428 


INDEX. 


Pago. 

Birds,  fossil 303,304 

nisoii,  fossil 211 

lilmk  Kock,  view  of  laku  terraces i 

lieiRht  of  shore-lines    365,370,372 

niea!*iiieiuenl  of  shorc-linoa 412,414,  417,418,419 

Hlack  Kot;k  beucb,  iustallation 231,409 

Unchnj; 232 

hoight 233,410 

map 3!to 

Black  Rock  gauge,  iuslallaiion 23 1 ,  409 

leveling 3:t2 

Iifight 233.410 

noord 233 

lUuckfoot  River,  possible  changes 219,203 

lUacksnjitb  Fork, superpoailion  of  embauktueuts  ...  151 

dt'ltas 162 

lUake,  William  P.,  cited 15 

Illoody  Cauyon  nioraiiios 313,  315 

Bouiioville  Basin,  description 20 

ninp  of  subdivisions 122 

bistory 214,316 

subdivisions 222 

possible  changes 262 

Bonnevilb'  beds  (see,  also,   White  Marl  and   Tello^v 

Clitii) 188 

llonnox  ille,  B.  L.  E.,  explorations 12 

Buuuevillo  fossils    209 

Bonne vilbi  Lake,  outline  at  highest  stage 101 

area  and  depth 105 

depth 125 

authorities  for  map 125 

outline  at  Provo  stage 127,128 

composition  of  water 204 

large  map (in  pocket  of  cover.) 

Bonneville  sliore-Une,  highest 91,  94,  97 

general  description 93 

clilfs  and  terraces 107 

V-embauknionts , 108 

spits  and  loops 108 

deltas. 109.153 

embankment  series Ill 

uncertainty  of  still-water  level  125 

near  outlet 174 

on  Pavant  Butte 326,328 

in  Esc.ilanio  Desert 362 

deformation 365 

height  at  various  points  365 

curves  of  equal  height 3G8 

synchronism ..  369 

(See,  also,  Intermediate  Hhore-lincs,  Provo  shore- 
line^ and  Stanshury  shoreline.) 

Box  Elder  Creek  deltas 163 

Braddock's  Bay 50,63 

Bradley,  Frank  H.,  observations  on  Lake  Bonneville.  10 

cited  on  ancient  delta  of  Ogdcn  River 93 

cited  on  terraces  in  Marsh  Valley 95 

cited  on  highest  shoreline 96 

cited  on  dt-ltas 153 

cited  on  i)utlet  of  Lake  Bonneville 173 

leveling  at  Ogden 412 

Branchinecta 259 

Brewer,  W.  H.,  cited 206 

Brigham  City,  deltas  near 163 

Brine  of  Great  Salt  Lake 251 

Bi  ine  of  Se vicr  Lake 226 


Page. 

Brine  shrimp 254 

Brodie,  James,  cited 270 

Uriickner,  Eduard,  cit*'d 271 

Burgess,  M.  F.,  leveling  data 412 

C.icho  Valley,  terraces 95,96 

Tertiary  lake  beds 99 

Bonneville  Bay .' 102,178 

del taa 1 59, 1 62 

fault  scarps 351 

Call,  R.  EUswctrth,  recent  and  fossil  shells  of  Great 

Basin 19,297 

Bonnrville  shells 210 

Campbell,  J.  F.,  cited 270 

Cedar  Range    103,128 

Cbadbtmrne,  P.  A . ,  cited    211 

CIiamberlin,T.  C,  cited 272 

Cbatard,T.M.,  analysis 207 

Christmas  Lake  fossils    303,  394 

Ciiurcb  Lake 300 

Cialdi,  Alessandio,  coast  processes 26 

tlieory  of  littoral  transportation 41 

City  Creek  deltas 164 

City  Creek  water,  precipitation  experiments 206 

analysis 207 

Clarke,  F.W.,  analyses 207 

Clarkstor,  fnult  scarps 351 

Clayton,  .I.E.,  cited 348 

CliiTs,  formation  by  waves 34 

classification 75 

comparison 75,  77 

Climate  and  interior  basins  3 

Climate  and  moraines 398 

Climate  curves  246 

Climate  of  (ireat  Basin  6 

Climate  of  lake  ejioeh,  as  inferred  from  fossil  shells.  297 

as  inferred  fritm  fossil  bones 303 

as  iiifeired  from  moraines 305 

Climatic  factors  affecting  lakes  and  glaciers 275 

Climatic  interpretation  of  lake  oscillations. 265 

Cloud-burst  channels. 9 

Coast  lines,  local  phases 60 

adolescent  and  mature. 63 

simplification 63 

of  rising  and  sinking  land 72 

Cold,  <-orrelation  with  buMiidity. 265 

corrt'lation  with  <lepauperation  of  shells  300 

Cnlm-ado  Desert,  ancient  lake 15 

Coi.e,  alluvial.     See  AUunial  cone  and  Alluvial/an. 

Confusion  Riiugo,  fault  scarp 353 

Connm,  P.E  .cited 228 

Coolidge,  Susan,  observation  of  oolitic  santl 169 

Cope,  E.  D.,  cited  on  Christ nins  Lake  fauna 303 

defuiition  of  Eqnus  fauna 394,400 

cited  on  age  of  Eqnus  fauna 397,  398 

cited  on  Pleistocene  climate 398 

Corinne,  height 411 

Correlation  by  means  of  fossils,  methods 398 

Correlation  of  lakes  with  glaciers 265 

Correlation  of  shore  lines  with  sediments 188 

Cottonwood  Creek,  deltas 165 

moraines 305.300,046 

fault  scarps 346 

niap 346 

Coulee  edge,  compared  with  other  cliffs 76,  77 


INDEX. 


429 


Coyote,  fossil 303,394,400 

Coyott^  Spring,  rhyolite 337 

Cratei's,  Ice  Spring 32U 

Pavaut 325,3.»8 

Tabernaele 328,320 

Funiarolo 332 

Crescent  crater 320,  322 

doll,  James,  cited- 284 

Crosby,  W.  O.,  theory  of  joint  structure 213 

Crust  of  the  earth,  strength 387 

Cub  Creek,  delta 102 

Clip  Butte,  view 54 

looped  embankment 169 

profile  of  shorelines 1^8 

shoreline  measurements 372,412,419 

Current,  theory  of  wind- wrought 29 

function  in  transporting  shore  drift 37 

function  in  funning  embankments 46,  47 

function  in  tliL>  biiihlingof  houks 52 

Curve  of  precipitation  change  for  Great  Basin 245,249 

Curve  of  rise  and  fall  of  Great  Salt  Lake,  annual 239 

non-pe  riodic 243,  240 

Curveof  secularclimalic  change  in  BonnevilleBa-in.  2G2 

Curve  of  temperature  change  for  Great  Basin 240 

Curves  of  etiual  height,  Bonneville  shore-lino 3C8 

Provo  shoreline 372 

Curves  of  snow-fall  and  melting 289,  293 

Curves,  theoretic,  of  post-Bonneville  deformation 374 

Cnt-and-built  terrace 30,40 

Cut-terraces,  mode  of  furmation 35 

of  Bonneville  shore-line 107 

of  Prove  shore-line 127,128 

of  Intermediate  shore-lines 144 

Cypris 210 

Dana,  Edward  S.,  bulletin  by 19 

Darwin,  G.  H.,  cited 387 

Datum  fur  gauges,  map 390 

Datum  jioints  connected  with  gauging  of  Great  Salt 

Lake : 233,409 

Davidson,  George,  cited 10 

D  ii  V  i  s,  W .  M . .  e  i  ted 1 80 

Dawk  ins,  W.  B.,  Pleistocene  mammals .  400 

Dead  Sea  history  and  glacial  liisLory 2G5 

Death  Valley 8 

Deep  C  reisk  Kange,  faults 353 

Deer,  fossil 211,303,394 

Deformation,  crustal,  by  loading  and  unloadini:  3.'i7,379 

of  Bimnoville  shore-line 'iG\  308 

of  Prnvo  slnire-lino 371,  372 

duiing  Prcivo  epoch. 372 

ipiestion  of  cause 373 

curves  of  theoretic 374 

nf  geoid 421 

of  Bonneville  Basin  by  expansion 42r> 

Degradation  clift"  compared  with  other  cliffs 75,  77 

Degradation  terrace,  compared  with  other  terraces  78,  81 

De  la  Bcche,  Henry  T.,  writings  on  shore  topography.  20 

variation  of  beach  profile 42 

Delta  terrace,  compared  with  other  terraces 84 

Deltas,  origin 65 

internal  structure 69,  70 

of  emergent  coasts 74 

of  Ogden  River 93 

of  Bonneville  shore-lino 109 


Pago. 

Deltas,  Provo  shore-line 129 

of  Lake  Bonneville 153 

history  deduced  from 166 

of  Spanish  Vork 343 

of  Weber  River 349 

Depauperation  of  lossil  sheiks  299 

De|>osition,  littoral    40 

Deposition    of    salts    by    desiccation,     Bonneville 

Basin 204.208,258 

Rush  Lake 2_'9 

Depth  of  Lake  Bonneville 125 

Di-pths  of  lakes,  table 100 

Desiccation,  deposition  by.     See  Deposil'ion. 

Desoi",  E.,  limitation  of  tidal  action   29 

cited  on  subaqueous  ridges  43 

Diastrophism,  defined 3 

and  interiiir  basins  304 

and  Lake  Bonneville 340 

of  Jordan  and  Tooele  valleys 307 

Diatoms  210 

Differential  degradation  cliff,  compared  with  other 

cliffs 75,77 

Differential    degradation    terrace,    compared    with 

other  terraces    78,  84 

Discrimination  of  shore  features.  74 

I>i.-*placement.     See  I>iastfophism  and  Deformation. 

DistiiUulion  of  basalt,  map 334 

Distribution  of  fault  scarps,  map 352 

Distribution  of  wave-wrought  shore  features 60 

Divides,  shifting  of 217 

Douris,  T.,  gauge  readings 235 

Dove  Creek,  sea-cliff  near ]07 

Bonneville  embankment  series 112, 114, 117, 120 

Provo  ombankment  series 131 

Intermediate  embankments 137 

map  and  view ]38 

embankment  interval 143 

superposition  of  emhanknieitts 151 

measurements  of  heights 372,  406,  419 

Drainage  system  of  Bonneville  Basin 21 

Drainage  system  of  Great  Basin 7 

Drew,  Frederic,  alluvial  fans HI 

Dry  Canyon,  fault  >carp 340 

Dry  Cottonwood  Canyon,  moraines 309,340 

fault  scarps 340 

Dug  way  Range,  ihyolite 338 

Dunderberg  Butte 335,330 

Dunes     ,S9 

Dunes  of  gvpsum 'Z'S.i 

Dunes  on  Sevier  Desert 332 

Dutch  Point 53 

Dutton,<'.  E.,  eitedoneauseof  aridity  of  Great  Basin.  10,  280 

cited  on  isostasy    388 

Karth  shaping     27 

Karlli,  strength  of  the  38? 

Earthquake  waves  and  joints 213 

E  irtli quakes    ;iGO 

East  Canyon,  fault  scarps 3.')2 

El  Moro,  Pleistocene  eruptions 337 

Elephant,  fossil 21 1,  303.  304,  394,  400 

Elevation  of  Bonneville  Basin  by  expansion 427 

Emergence,  effect  on  shores  72 

Embankment,  compared  with  other  ridges 87 

Embankment  series,  Bonneville  shore-line 111,369 


430 


INDEX. 


Embankment  serios,  Provo  sliore-liuo 131, 132 

ErabankmentH,  littoral 46 

rhythmic 73,  137 

i»f  Bonni'villo  Mbore-line 1U8 

of  I'rnvo  Hliort'-lino 127, 131, 132 

of  InteinuMliato  shore-lines 135 

conipouml 144 

calcareouM  cement 107 

Emmons,  S.  F.,  iuvestigation  of  Pleistocene  lakes  ...  17 

cited  ou  hijjbest  shore-lino  90 

(;ite(l  on  Tertiary  in  Rush  Valley 99 

cited  on  Litt!«  Cottonwood  glaciers 305 

Empire  BlutT.i 50 

Eiidlirh.F.M.,  cited. 2C8 

Engelmann,  Ilt-nry,  iuveHtigalionof  Lake  Bonneville.  15 

lionrieville  shells    209 

Eocene  lake  beds 90 

Epcirogeny  defined 340 

Ephedra  jrracilis 259 

E' 111 i potential  surfaces 421 

Etiuus  fauna,  question  of  age 393 

Erowion  by  waves .   .  29 

Erosion  cliff,  compared  with  other  cliffs 75,  77 

Erosion  terrace,  compared  with  other  terraces 78,84 

Eruption,  recency  of  latest 324 

Escalante  Basin,  map 122 

Escalante  Bay,  depth 125 

question  of  synchronism 369 

Escalante  Desert,  barometric  measurements 362,406 

heights  of  shore-lines 366,  415,  417, 418 

Escalante  Lake,  theory  of 363 

Escalante,  Padre,  explorations   12 

Sevier  Lake 224 

Evaporation  formula 285 

Evaporation  rate  in  Great  Basin 7 

Expansion  as  a  cause  of  post  Bonneville  deformation.  377, 427 

Experiments  in  precipitation  of  sediments 205 

Falsan,  A.,  cited 271 

Fans,  alluvial 81 

Farmiugton,  installation  of  lake  gauge 231,232,409 

height  of  gauge 233,410 

record  of  lake  level 234 

observations  of  lake  changes 240 

fault  scarp 349 

bench-mark 409.410 

Fault  scarp,  compared  with  other  cliffs 76,  77 

Fault  scarps,  of  Bonneville  Basin 3t0 

map  showing  distribution 352 

general  features 354 

tlates  of  foi-mation 356 

relation  to  *'arth<iuakes 361 

Fault  terrace,  cornpan'd  witli  other  terraces 83,  84 

Faults  of  Jordan  and  Tooele  Valleys 367 

Fauna,  Eijuus 393 

Fauna  of  Great  Salt  Lake 258 

Faye,  11. ,  cited 387 

Felix.  J.,  Pleistocene  lakes  of  Mexico 402 

Fetch  of  waves 43.107 

Fetch  of  waves  on  Lake  Ontario 53 

Fillmore,  volcanic  field  near 320 

height  of  Bonne  vile  shoreline 366,  417 

barometric  station 406,  415 

Fish  Spring,  fault  scarp 353 

shore-line  measurements 372,412,419 


Page. 

Fisher,  O.,  cited   388 

F'ive  acre  Creek 174 

Fleming.  Sandford,  on  process  of  littoral  transporta- 
tion    26 

on  Toronto  Harbor. 53 

on  retreating  embankment 55 

Flow  of  solids   383 

Fluminieola  fusea 302 

Folded  strata  under  Logan  di-Ua 162 

Fort  Douglas,  fault  scarp    347 

measurements  of  shore-line  362,  412,  413,414 

height  of  Bonnevillo  shore-line    365,417 

Fortieth  Parallel  Exploration,  investigation  of  Pleis- 
tocene lakes    17 

Neocene  lake  beds 99 

credit  to  maps  126 

survey  of  Great  Salt  Lake 230 

map  of  Great  Salt  Lake 243,244 

Fossil  Lake 394 

Fossil  mammals  and  iSonneville  climate 301 

Fossil  shells,  evidence  as  to  Pleistocene  climate 297 

depauperation  300 

measvirementa 302 

Fossils  of  Christmas  Lake 394 

Fossils  of  Lake  Bonneville 209 

Fossils  of  Lake  Lahontan 395 

Fox.  Jesse  W.,  leveling  at  Black  Kock 232 

FranUland.E.,  cited 284 

Franklin  liutte,  discrepant  shore  records 124 

heights  of  .shorelines 365,370,372 

measurement  of  heights 412,413,417,418,419 

Fremont,  J.  C.,  the  name  Great  Basin 5 

explorations    12 

tufa  near  Pyramid  Lake 13 

Antelope  Island  liar 241 

Fremont  Island  terraces 13 

Frisco  Jlange,  V-bars 58 

alluvial  cones  and  shore-lines 92,  93 

Fuaiarole  Butte  and  lava  bed 1 82, 3o  w 

Gale,  L.  D.,  analysis  of  water  of  Great  Salt  Lake  . . .         2-i3 
Gannett,  Henry,  cited  ou  Bear  River  drainage 218.219 

altitudes  364 

Garfield  Landing  Gauge,  installation 231,409 

renewal 232 

height  of  zero 233,420 

record 235 

Garn,  E  ,  Lake  Shore  gauge 231,234 

GastaMi.  cited 271 

Gate  of  Bear  River 178 

Gauging  Great  Salt  Lake 2^0,409 

Geikie,  Archibald,  cited  272 

Geikie,  James,  cited  271,274 

Gentile  Valley,  terraces 95,96 

alluvial  depo?iit3 103 

Geoidal  deformation 376,421 

George's  ranch,  embankment  series 112, 113, 114 

auuient  delta  near 166 

Gervais,  Pliocene  mammals    400 

Glacial  epochs,  correlation  with  lacustrine  epochs  ..  263 

num))er  of 270 

Glacial  history  of  Great  Basin  bipartite 318 

Glacial  Period.     See  PUintocme. 

(Jlacial  streams,  deflection  of 315 

Glaciated  districts  of  the  Bonneville  Basin  374 


INDEX. 


431 


Page. 

Glaciation  and  aolar  radiation 283 

Gleu  Iloy,  ancieot  shores  aili)lencent  65 

Gouilfelloff,  George  E.,  Sonora  onrtliqiiake 361 

Gouseborry  Creek n7 

Gopher. fo3sil  303,304 

Gosiiite  Ranjie,  fault  s*^ sir p  353 

Graces,  Padre 12 

Graiul  Canyon  of  the  Colorado,  vohirae  301 

Giauite  Kock,  canyons  and  .shorelines 9  J,  03 

Giants ville,  map  of  shore  embankmeuts 131 

lateriueiliato  e.nibankiuents ...135,139,143 

traditional  history  of  Great  Salt  LaliO  211 

lueasuroment  of  shore-lines  372, 408,  410 

Groat  Basin,  described .-- 5 

ami  its  Pleistfieene  Likes,  map 6 

climate 6 

vegetation  9 

cause  of  aridity 10 

compared  with  interiorbasinaof  othercontinenta.  12 

history  of  exploration 12 

minor  basins 20 

climare  curvea 246 

recent  and  fossil  ahella 297 

mountain  structure    340 

Pleistocene  climate 398 

Great  Basin  Division,  organization  and  work xvii 

field  work  on  Lake  Bonneville   18 

publications 19 

Great  Britain,  Pleistocene  fauna 390,400 

Great  Salt  Luke,  evaporation  rate. 7 

view  on  shore 35 

map  of  hydrographic  basin 122 

oolitic  sand  169 

surveys 230 

depth 230 

gauging 230,  409 

recorded  rise  and  fall 233 

annual  rise  and  fall '- 239 

traditional  rise  and  fall 239 

changes  in  area 243 

corapar.itive  map 244 

cause  of  rise  and  fall 244 

future  changes : 250 

saliuo  contents 251 

sources  of  saline  contents 254 

rate  and  period  of  salt  accumulation 255 

fauna 259 

position  on  plain 372, 384 

Great  Salt  Lake  Desert,  lacustrine  origin 214 

surface 222 

view  of  lost  mountains 320 

Gr.at  Valley  of  Tennessee,  volume 391 

Greeley,  A.  AV.,  cited 7 

Gypsum  play  a  and  dunes 223,  320 

ILule  of  Kock  Canyon  faults 345 

Uiigue,  Arnold,  investigation  of  Pleistocene  lakes.. .  17 

cited  un  highest  shore-line 96 

Hand  level 411 

ILuiu,  Julius,  cited 284 

Hayden,  F.  V.,  observations  on  Lake  Bonneville 16 

cited  on  Bonneville  beds 188 

Bonneville  shells 209 

Hayden  Survey,  Neocene  lake  beds 99 

Hector,  James,  cited 361 


Pago. 
Height  differences,  Bonneville  and  Provo  shore-lines.  372,419 

Height  of  first  water  mnximuni 199 

Heights  of  IJunnevillo  slmrelinr,  tables   365,417 

Ht'ights  of  Provo  shore-line,  tables 370,  418 

Heights  of  shitr.'-line.*, 362,405 

Ileury,  I).  Fiiriand,  evjii)orati(m  from  LakeMichigan.  7 
Henry,   Jo.seph,    promotion   of  research  concerning 

Great  Salt  L:iko  231,240 

Henrj'  Mountains,  volume 390 

High  Creek,  delt  I 163 

Hind.  H.  Y.,  chart  of  Toronto  Harbor 54 

History  and  seijuenceof  Bonneville  shore-lines  169 

History  of  Bonneville  Basin 214 

History  of  Bonneville  oscillations 259 

History  told  by  deltas 166 

History  tuld  by  River  Bed  and  Leniington  sections. .  197 

Hitchcock,  Edward,  classification  of  stream  lenacea.  80 

Hitchcock,  Charles  H.,  explanation  of  lake  ramparts.  71 

Hobble  Creek,  deltas 165 

fault  scarps 344 

Holmes,  William  H.,  sketch  of  shorelines  on  Oquirrh 

Range i 

sketch  of  fault  scarps 348 

Honey  Lake 300 

Honey  ville,  fault  scarp 351 

Hook,  origin  and  character  52 

on  Lake  Michigan,  view 52 

at  Willow  Springs 145 

Hopkins,  power  of  currents 41 

Hoiiznntaiity  of  shorelines  88 

Horse,  fossil  303,394,400 

Hot  Springs,  near  Fumarole  Butte  333 

near  Salt  Lake  City 349 

near  village  of  Bonneville 350 

House  Range  (see  also  Fish  Springs) 353 

Howell,  Edwin  E.,  field  work  on  Lake  Bonneville 17 

cited  on  highest  shore-line    96 

cited  on  deltas 153 

cited  on  outlet  of  Lake  Bonneville 173 

measurement  of  shore-lines 362 

theory  of  Escalante  shore-line 363 

shore-line  in  Escalante  Desert 370 

Hoxie,  R.  L.,  survey  of  Sevier  Lake 225 

Hualapi  Valley 11 

Humidity,  correlation  with  cold 2G5 

local,  in  relation  to  glaciation  278 

law  of  vertical  distribution  284 

Hungerford,  E.,  welding  of  snow 290 

Hunt'sranch 174,178 

Hydrographic  basin.     See  Basin. 

Hydrography  of  Bonneville  Basin 21 

Hydrography  of  Great  Basin 7 

Hydrostatic  law  in  orogeny 357 

U^  psometric  data 405 

Hyrum,  delta  terraces 163 

Ice  Spring 325 

Ice  Spring  craters  and  lava  field 320 

Ice  Spring  craters,  view 322 

Ice  Spring,  fault  scarps 325 

Ice- wrought  shore  ridge 71 

luter-Bonneville  beds 192, 194 

Inter-Bonneville  epoch 261 

Intf  rior  basins,  causes 2 

in  Arizona,  New  Mexico,  and  Texas   11 


432 


INDEX. 


Page. 

Intermodiato  Hhorn-linea,  description 135 

discussion  of  cmbaukmuiits 137 

cut-terraces , 144 

Inyo  earthquake 301,362 

Irri<:ation  and  Great  Salt  Lake 2\Q 

Irrigatinn  and  Sevier  Lake 227,250 

Islands  nl"  Likii  lioiuieviUe,  miiin  body 102 

Sevier  body 10'> 

Isoatasy 387 

Jiimiesou,  Tbomaa  F.,  cited 265 

Johnson,  Willard  D.,  field  work  on  Lake  Bonneville.  18 

map  of  bay  bars  iu  Snake  Valley 112 

survey  of  White  Valley  Bay 126 

map  of  I^of;au  River  delta  terraces 160 

map  of  KimI  Kock  Pass. 174 

map  of  Old  liiver  Bed 182 

map  of  portion  of  Old  River  Bed  194 

exidoration  of  Sevier  Lake  salt  beds 225 

map  of  Sevier  Lake  and  salt  beds .   227 

Joint  atrtictnre  .  211 

Jones,  Marcus  E-.iiauging  Groat  Salt  Lake  232,237 

Jordan  Kiver,  Tertiary  lake  beds 99 

irrigation 250 

anal^-ais  of  water 254 

Jordan  Valley,  diastrophism 307 

Joidati- Utah  Bay 103 

Juab  Valley  Bay 103 

Juab  Valley,  fault  scarps 343 

Kamas  Prairie,  change  of  drainage ,...  218 

Kame.s,  cou)i)ared  with  other  ridgea 87 

Kanab  Creek,  I'leistoceue  eruption 337 

Kanosh,  measurement  of  height 408,415,417 

Keller,  H.,  on  littoral  processes 26 

Kelton  Butte,  view J08 

discrepant  .shore  records 124 

heights  of  shore-lines 365,  370,372 

measurement  of  f*hore-lines 400,419 

King,  Clarence,  aeknowledgmi  iits  to    xv 

investigation  of  Pleistocene  lakes 17 

cited  on  highest  shore-line yc 

Eocene  near  Salt  Lake  City 100 

citetl  on  correlation  of  sedimentsand  shorelines.  189 

fossil  mammals 2!1 

brine  of  Croat  Salt  Lake...- r.52,  254 

cited  on  correlation  of  lake  epochs  with  glacial 

epochs 267 

cited  on  ;;i.u'iation  and  heat 284 

tlieory  of  Esi-alante  shore-line 363 

Ring  Survey.     See  Fordrth  Parallel  Exploration. 

K noli  Spi ing,  fault  sca?p 353 

Knowl ton's  ranch,  fault  scarji 352 

La  Sal.  Sierra,  volume 390 

Lagging  of  lakes  behind  glaciers 314 

Lahontan  llnsin.  conipletii  dusiucation  ....: 258 

Lalumian  mamtnalian  fauna 395 

Lake  basins 2 

Lake  beds 188 

Lake  beds  intorslratilied  with  delta  gravels 150 

Lake  Bonneville.     See  Bonneville  Lake. 

Lake  Creek 185 

Lake  formerly  in  Colorado  Desert 15 

Lake  rampart,  mode  of  forma tiou 71 


Page. 

Lake  rampart,  compared  with  other  ridgoa 87 

Lake  ridges  iu  Ohio 43,44 

Lake  shores,  topographic  features 23 

Lake  Point,  fault  scarp 35*^ 

Lake  Shore  gaug  ■,  installation 231.409 

connoction  with  other  gauges  2'Ai 

litught 233.364,410 

record  234 

Lakes,  Plei.stoceue, of  the  Great  Basin, map- 6 

of  Great  Basin  8 

earlier  than  Bonneville 98 

table  of  dimensions 106 

correlation  with  glaciers , 265 

Land  sculpture 27 

Landslip  cliff,  compared  with  other  cliffs  77 

Landslip  teirace.  compared  with  other  terraces 83.84 

Lartet,  Loui.s,  cited 205 

Lattimore,  S.  A.,  analyses  of  Sevier  Lake  desiccation 

y>roduets , 220 

Lava  field,  Ice  Spring 320 

Pavant  Butte 328 

Tabernacle 329 

Furaarole 332 

Lava,  liquidity 322 

Lee,  C.  A,,  lake  rampaits 71 

Leevining  Creek,  glacial  moraines 312 

Leniington,  geologic  section 192 

record  of  first  water  maxiiniim 19!) 

height  ot  shoreline 36'. 

measurement  of  heights ...411,  412,  414,  417 

Lenk,  11.,  Pleistocene  lakes  of  Mexico 402 

Level  of  still  water 122 

Leveling,  account  of  work 304,411 

probable  error 417 

Limuiiphysapalustris  300,  301 

Little  Cottonwood  Creek,  ancient  delta  165 

moraines 305,306,340 

fault  scarps 34© 

map  340 

Lit(le(iull  Lake yoo 

Littoial  deposition , 40 

Litloral  erosion  29 

Littoral  topoijiapby 23 

Litttnal  trausjiortation    37 

Llam;is,  fossil 303,391,400 

Loading,  unhiadiiig,  and  tlefnriuation 357,379,  421 

Loew,  t»scar,  analysis  of  Sevier  Lake  water 220 

Logan,  deltas  if,ip 

map  of  deltas inu 

view  of  del  [as 102 

I'.iitlt  seatp 351 

heights  of  shore-lines 365.  370,  372 

measurement  of  heights 411,412,413,417,4:8.41!) 

Lone  Pine,  tarthipiake 361.302 

Loops,  origin  ami  eharacler 55 

outline  maps 5g 

of  Bonneville  shore-line 109 

Lost  mountains 215,  320 

Lower  River  Bed  section 189 

Lyell.  Charles,  method  (.f  Tertiary  clas8t6cfttion  39H 

cited  on  principles  of  e(u relation 401 

Main  body 101,122 

Major,  C.  I.  Forsyth,  Pliocene  niamm.ils 4O0 

Malade  Valley  Bay 102 


INDEX. 


433 


Page. 

Mammalian  fossils,  from  Eonnevillo  beds 210 

and  Bonneville  climate 303 

from  Christinas  Lake 394 

Map  of  Lake  Bonneville,  autborities 125 

Marcet,  W.,  brinoof  Great  Salt  Lake 254 

Markatjunt  Plateau,  Pleistocene  eruptions 336 

Marsh  Creek,  description 174 

alluvial  terrace 175 

lower  course 176 

alternation  of  tribute 178 

fault  scarps 351 

Marsh,  O.  C,  cited  on  Equus  fauna 393,  395 

Marsh  Valley,  terraces  i'5 

general  features 17G 

Matching 399,402 

Matlin,  Tertiary  lake  beds 99 

measurement  of  heights 372,  40C,  419 

Mature  coast  lines 03 

McGee.W.  J.,  field  work 18 

oolitic  aand 169 

cited  on  number  of  glacial  epochs 272,  274 

cited  on  deflection  of  glaciers 315 

Equus  fauna 393 

McKay,  Alexander,  cited 361 

Meadow  Creek,  measurement  of  heights 408,415,418 

Measurements  of  shore-line  heights. 362,  405 

Melting  curve 289,  293 

Mexico,  Great  Valley 402 

Michigan  Lake,  evaporation 7 

subaqueous  ridges 43,  44,  45 

view  of  bay  bar 48 

bay  bar 50 

hook  at  Dutch  Point 53 

Mil  ford,  height  of  Bonneville  shore-line 365 

raeasurement  of  heights 408,  411, 412, 415, 417 

Mill  Creek,  moraines 311 

Miller,  Hugh,  classification  of  stream  terraces 80 

Miller,  Jacob,  Farmington  gauge 231,234 

rise  and  fall  of  Great  Salt  Lake L'40 

soundings  on  Antelope  Island  bar 211 

Mimbrcs  Basin 11 

Mitchell,  Henry,  formation  of  beaches 26 

Mitchell,  John  T.,  gauge  observations 231,233 

Miter  Crater 321, 322 

Mohave  River 8 

Molluflks,  from  Bonneville  beds 209 

and  Bonneville  climate 297 

from  Christmas  Lake 395 

Mono  Lake,  observations  by  J.  D.  AVhitney 16 

Mono  Valley,  shore-lines  and  moraines 306,  311 

Pleistocene  eruptions 337 

Montanari,  theory  of  littoral  transportation 41 

Montpellier,  Pliocene  fauna 399,  400 

Moiaine  terrace,  compared  with  other  terraces 81,  84 

Moraines,  compared  with  other  ridges 86,87 

and  ancient  shore-lines. 305 

and  fault  scarps 346 

and  climate 398 

Morgan  Valley.  Tertiary  lake  beds 99 

bay  of  Lake  Bonneville 103 

fault  scarp 351 

Mountains,  of  Bonneville  Basin 91 

view  of  buried 320 

growth  of 359 

Muddy  Pork,  deltas 162 

MON  I 28 


Page. 

Murray,  John,  cited 12 

Musk  ox,  fossil 211,  303 

Mylodon  sodalis 391 

Neocene  and  Equus  faunas 393 

Neocene  geography  of  Bonneville  Basin 214 

Neocene  lake  beds 99, 173 

Nell,  Louis,  survey  of  Sevier  Lake 225 

New  Garfield  gnage 232,233,237 

New  Mexico,  interior  basins 11 

Pleistocene  eruptions 337 

New  Zealand,  earthquakes 361 

Newberry,  John  S.,  cited  on  number  of  glacinl  epochs  272,  273 
Nomenclature,  geologic 22 

Ocean  currents  in  relation  to  glaciation 281 

Ogden,  altitude 3tJ4 

height  of  Bonneville  shore-lino 365 

measurement  of  shore-lines 411,412,  413,417 

Ogden  Canyon,  fault  scarps 350 

Ogden  Piver,  ancient  deltas 93,  163 

Old  River  Bed,  map  of  V-embankments 58 

description 181 

map 182 

lower  section 189 

upper  section 194 

geologic  map  of  portion 194 

Ombe  Range,  Tertiary  lake  beds 99 

island  in  Lake  Bonneville 102 

Ontario  Lake,  headlands  and  bay  bars 50 

fetch  of  waves  reaching  Toronto 53 

simplification  of  coast-line 63 

distribution  of  mature  and  adolescent  coasts  ...  65 

Oolitic  sand 169,252 

Oquiri  h  Range,  view  of  lake  terraces i 

fault  scarps 352 

Oregon,  Equus  beds 394,  397 

Orogeny  discriminated  Irnm  epeirogcny ,  ...  340 

Oaar,  compared  with  otlier  ridges 87 

Otter.fossil 303,304 

Outlet  channels,  characters 171 

relation  to  shore-lines 186 

Outlet  of  Lake  Bonneville,  description  171,173 

literature 173, 182 

map 174 

view 176 

question  of  earlier 1 80, 216 

Owen,  Fred.  D.,  general  assi.'itant 18 

sketch  of  head  of  Tooele  ^nlley 96 

Owen's  Valley,  earthquake 361,  362 

Ox,  fossil 303 

Packard,  A.  S.,  cited  on  Old  River  Bed 182 

fauna  of  Great  Salt  Lake 258 

Pahoehoe,  Pavant  Butte 328 

Tabernacle  Butte 330 

Paleoutologic  evidence  on  ago  of  Equus  fauna 397 

Paleontologic  methods  of  correlation 398 

Parallel  Roads  of  Glen  Roy 65 

Park.  John  R.,  gauging  Great  Salt  Lake 231,  409 

Park  Valley  Bay 102 

Pass  between  Tooele  and  Rash  valleys,  description  52, 97 

map  of  hook 58 

view 96 

map 138 


434 


INDEX. 


Pass  between  Tooele  and  Hash  valleys,  saperposition 
of  embankments 

ancient  river    

Pavant  Butte,  descnption 

view 

height  of  Bonneville  Hhore-liue 

measurement  of  shore-lines -108, 

Pavant  Kange 

Pa.vsoii,  di'lta  near 

Peale,  A .  C,  observations  on  Lake  Bonneville 

cited  on  shoreline  higher  than  the  Bonneville  .. 

cited  on  outlet  of  Lake  Bonneville ^ 

cited  on  age  of  Bonneville  beds 

Penck,  Albreeht,  cited 

Physa  ampullacea 

Physa  gyrina 

Physiographic  evidence  on  ago  of  formations 

rhywingraphy 

Pilot  Peak,  terraces 

Pink  Cliff  formation  on  Sevier  liivcr 

Pinto  Cauyou,  measurement  of  heights 408, 

Plant,  fossil 

Playa  de  los  Pimas 

Plaj'as  of  the  Bonneville  Basin 

Pleistciceue,  shortest  of  the  periods 

lakes,  map 

name  preferred  to  Quaternary 

climate 

volcanic  eruptions 323, 326,  330, 

winds 

Eqiius  fauna 

two  uses  of  term  

mammalian  fauna,  Great  Britain  

lakes,  Mexico 

(See,  also,  Bonneville  beds.  White  Marl,  and  TeUo^v 
Clay.) 

Pliocene  and  Equus  faunas 

Pliocene  fauna  of  Aruo  Talley 

Pliocene  fauna  of  Montpellier 

Point  of  the  Mountain,  lu-.tn  of  V-bar 

sca-elitf 

iiue(|ual  I'liibankuK-nts 

piolilu  uf  omhankuR-nts 

heights  of  shore-lines 365, 

measureuient  of  shore-linos 411,412,414,  417, 

I*noU',  Henry  S.,  obsei-vatious  on  Lake  Bonneville. . . 

Portage,  didta  near 

Portnenf  lliver,  terraces 

lower  canyon 

in  Marsh  Valley 

possible  chiingos 

Post -Bonneville  history 

Powell,  J.  W.,  acknowledgment  a  to 

cited  on  yonth  ()f  high  mountains 

Powell  Survey,  fiild  work  on  Lake  Bonneville 

gauging  Great  Salt  Lake 

Pratt,  John  H.,  cited 

Pre- Bonneville  history 

Piecipitati(m  and  interior  basins 

in  Great  Basin 

secular  curve  for  Great  Basin 

Precipitation  of  sediments.  expL-riments 

Prenss  Lake 

Preiias  V:illey,  V-hars 

map  of  east  side 


149 

184 

325 

328 

366 

415,417 

319 

165 

18 

94,95 

173 

267 

271 

300 

301 

396 

27 

144 

99 

415,418 

210 

11 

222 

1 

6 

22 

265 

336,  338 

332 

393 

395 

399,  400 

402 


393 

399,  400 

399,  400 

58 

107 

123 

138 

370,  372 

418,419 

16 

16ii 

95 

96 

176 

219 

222 

XV 

350 

18 

230,  409 

387 

214 

4 

(i 

245,  246 

205 

2J4 

58, 121 

92 


Pago. 

Preuss  Valley,  discrepant  shore  records 124 

maps  of  embankments 136 

embankments 137 

profiles  of  embankments 138 

interval  between  embankments 141, 143 

double  series  of  embankments 152 

record  of  tirst  water  maximum 109 

measurement  of  heights 372,412,419 

Probable  errors 4 16 

Profiles,  Bonneville  Bay  bars 116 

Provo  shore-line 132 

Intermediate  embankments 137, 138 

Promontory  Mountain,  an  island  in  Lake  Bonneville.  102 

at  the  Provo  stage 128 

heights  of  shore-lines 306,  370,  372 

measurement  of  shore-lines  412,413,417,418,  419 

Provo  epoch,  displacements 372 

Provo  River,  sucieut  deltas 153, 165 

change  of  course 218 

Provo  shore  line,  north  end  Oquirrh  range,  view i 

origin  of  name. 120, 153 

outline  and  extent 127 

later  than  Bonneville  shore-line 127 

cut-terraces 128 

deltas 129,153 

underscore 130 

embankment  series 131 

area  included 134 

map 134 

tufa 167 

on  Pavant  Butte 326 

on  Tabernacle  lava  field  330 

altitudes  at  various  points 370,418 

deformation 371 

curves  of  equal  height 372 

Publication  of  work  of  Great  Basin  Division   XVII,  19 

Quaternary.     (See  Pleistocene.) 

Kailroad  altitudes 411 

Kainfall,  interior  h.isius  aiul 3 

of  Great  Basin  6 

secuhir  curve  f^r  Great  Basin 245.246 

Uanipart,  mode  of  formation 71 

comparctl  with  otlu^r  ridges 87 

Kamsey,  precipitation  of  sediments 20<i 

liankine,  W.  J.  Mc<i.,  theory  of  waves 26,29 

lied   Uock  Pass,  Bonneville  mitlet   173 

question  of  pre- Bonneville  outlet 216 

height  of  shor»'-liue 3(15 

moasurenieTit  of  heights 411,  412,  417 

Ueilding  Spring,  view  of  shore  t<'rrace Il'tt 

Ueindrrr,  fossil 211 

Uelalive  huiiiiility,  Great  Basin 6 

law  of  vertical  distribution  284 

Reservoir  Butte,  map  of  embaukuienta 58 

description 110 

superposition  of  embankments  148 

nuip 148 

view 148 

tufa 169 

Rhyolitft    337 

Uhythmic  embankments,  conditions  of  formation. . .  73 

of  Lake  Bonneville 137,141 

Richthofcn,  F.  von,  on  littoral  processes 26 


INDEX. 


435 


Page. 

Eichthofen,  F.  von,  on  characters  of  a  senile  coast. ..  64 

Ricksecker,  Eugene. 18 

Ridge,  8ubaqueon8 43 

Rid;;es,  classification  and  comparison 86 

Rigidity  of  earth's  cr  .st 358,387 

Kiver  Bed.    (See  Old  River  Bed.) 

River  Bed  section,  lower 189 

u])per -  194 

River  water  analyses 207,255 

River  nioutb  bars 49 

Rivers,  ancient 171.181,184 

Rivers  of  Bonneville  Basin 21 

Roan  Mountain,  volume 390 

Rock  Canyon,  deltas 105,344 

fault  scarps    344 

Routes  of  e*'olo^ic  exploration,  map 18 

Rush  Creek,  moraines  313 

Rush  Lake,  remnant  of  Lake  Bonneville  14 

map 138 

inanold  rivercUannel 184 

history 228 

Rush  Valley,  Tertiary  lake  beds 99 

fault  scarps  352 

Russell,  Israel  C,  field  work  on  Pleistocene  lakes. . .  18 

publications  on  Pleistocene  lakes  19 

cited  on  cut-and-built  terrace    30 

cited  on  subaqueous  ridges 44 

photograph  of  bay  bars   48 

photograph  of  hook  52 

contributions  to  Bonneville  map lliO 

cited  ou  American  Fork  delta 155 

cited  ou  disturbed  strata  under  Log-in  delta 161 

experiments  in  precipitation  of  sediments 205 

cited  on  deposition  by  desiccation  209 

observations  on  joint  structure  ... 212 

gypsum  dunes 223 

collection  of  Sevier  Lake  salt 225 

leveling  at  Black  Rock 232 

desiccation  of  Lahontan  Basin 258 

Lahontan  history 264 

cited  on  history  of  Lahontan  climate. 267 

Lahontan  fauna 297 

Christmas  Lake  beds 303.394 

cited  on  history  of  ilono  Basin 306, 311 

cited  on  deflection  of  glaciers   315 

map  of  Fillmore  volcanic  district 320 

fault  scarps  of  Great  Basin  341 

salt  deposited  from  Great  Salt  Lake 257 

Equus  f  luna 393 

Rus-sell,  J.  Scott,  theory  of  waves 26,29 

Russell,  Thomas,  cited  on  evaporation  in  Great  Basin.  7 

Salinity  and  depauperation 301 

Salt  Creek  delta 165 

Salt  deposit,  Snake  Valley 223 

SeviL*r  Lake 225,22(r 

Great  Salt  Lake 257 

Salt  Lake  City,  Tertiary  near 100 

The  Bench 164 

fossil  musk  ox 211 

fault  scarps 347 

earthquake  prophesied 362 

measurements  of  shore-lines 362,  412,413,  414 

height  of  Bonneville  shore-line 365, 417 


Page. 

Salt  Lake  City,  barometric  base  station  400,  413,  414 

Salt  of  Great  Salt  Lake 253 

San  August  in,  Plain  of 11 

San  Francisco,  temperature  curve 246 

San  Francisco  Mouulaiu,  volume  390 

San  Francisco  I'lateau,  Pleistoceno  eruptions 337 

San  Jose  Kivtir,  Pleistocene  ertiptions 337 

Siinford,  W.A.,  Pleistocene  manunals 400 

Sautaquin,  height  of  sbore-lino 'lO.^ 

measuroiuuut  of  shorc-Uuo 411, 412,  414, 417 

Savage,  C.  R.,  photograph  of  Sheep  Rock 35 

Scarboro  Cliff 54 

Schott,  Charles  A.,  tables  of  precipitation  and  tem- 
perature  245,247 

Scirpus 210 

Scoriai,  Ice  Spring    323 

Dunderberg  Butte 336 

Sea  level,  dt'formation    421 

Sea-cliff,  origin. 34 

compared  with  other  clififs  77 

Sea-cliffs,  view  on  Oquirrh  Range I 

of  Bonneville  shore-line 107 

of  Provo  shore-line 129 

Sections  of  Bonneville  beds 189 

Sections  of  Sevier  Lake  salt  bed 225 

Senile  coast 64 

Sevier  Basin,  map 122 

Sevier  body  of  Lake  Bonneville,  described  104 

depth 125 

Sevier  Desert,  volcanic  districts 319 

rhyolite 337 

SevierLake,  description  and  history 224 

salt  bed 225 

map 227 

Sevier  River,  ancient  deltas 166 

shifting  of  divide 217 

Shasta,  volume  of  Mount 390 

Sheep  Rock,  view    35 

map 390 

Shells,  Bonneville 209 

of  Bonneville-  Lahontan  area 297 

Christmas  Lake 395 

Shoal  Creek,  measurement  of  height 408, 415, 419 

Shore  deposition 46 

Shore  drift  defined 38 

highway  of , 39. 40 

method  of  accumulation  in  embankments 46 

wasteof 39.40 

Shore  features,  description 23 

distribution 60 

discrimination 74 

Shore  wall 71 

Shore-line,  highest 94 

faulted   362 

Shore-lines,  ancient,  in  Ohio 43, 44 

detection  and  tracing 88 

of  Lake  Bonneville 90 

on  Frisco  Range 92 

on  Granite  Rock 92 

perishable 101 

and  outlets 186 

correlation  with  sediments .--.  188 

near  Salt  Lake  Citv,  vii'W 348 

ancient,  of  Christmas  Lake 394,  396 


436 


INDEX. 


Page. 

Shore-lines,  measuromen  I  of  hcij^hta 405,416 

Shores,  topographic  featiire.sof 23 

adolesceut  aurl  luaturo 63 

Sierra  la  Sal,  volume 390 

Sierra  Ni-vada,  Pleistocene  eruptions. 337 

earthquake  and  fault  scarps 361 

Siurra  Nevada  glacier;^  aud  Mouo  Lake 300,311 

Sigual  Service,  cited  on  cliniatu  of  Great  Basin 7 

observations  at  Salt  Lake  City 400 

Simpson.  J.  H.,  (diservaticm  of  ancient  shorelines. . .  ir> 

Skull  Valley,  embankment  aeries 112,113,122 

Shith.  fossil 303 

STiiitli,  R.  II.,  barometer  ohse.rver 407 

Smitliliold  Creek,  delta , 162 

Snake  Valley,  map  of  V-bars 58 

bay  of  Lake  Bonueville 104 

V-embaukmeiits 108 

embankment  series 111,112 

salt  marsh 223 

fault  scarps 353 

Snowfall  Curve 289, 293 

Snow-plow,  map  of  V-bar 58 

embankments. 137 

map  and  view 138 

embankment  intervals 141,143 

supei'ijositiou  of  emb  nkmenta 147 

measurement  of  shore-lines 372,  412, 419 

Snows ville  Valley,  river  channel 185 

Bonneville  beds  191 

fault  scarp 351 

measurement  of  shore-lines 406,419 

Sodium  sulphate,  precipitation  fromGreatSaltLake.  252 

Sonora,  eaithquake 361 

Spanish  Fork,  deltas 153,165,343 

fault  scarps 343 

Spirit-level  measurements 364,411 

Spits,  mode  of  formation  47 

of  Bonneville  shoreline 108 

near  Grants  ville,  map 134 

Spring:  Creek,  deltas 162,168 

Stansbury,  Howard,  cited  on  shores  of  Lake  Bonne- 
ville    13 

map  of  Rush  Lake 228 

survey  of  Great  Salt  Lake 230 

map  of  Great  Salt  Lake 243,244 

brine  of  Great  Salt  Lake 251,254 

Stansbury  Island  bar 241,243 

Stansbury  shore-line,  described 134 

tufa 167 

bypotUetic  explanation 186 

height 418 

Stelling,  formula  for  evaporation 2S5 

Sternberg,  C.  H.,  collection  of  fossil  bones 303 

Stillwater  level 122 

Stockton,  shore-lines  near 52 

V-bar 58 

view  of  shore-lines  97 

IntermedialL'ombankmonta 137, 138, 149 

map 138 

height  of  shore-lines 365,370,372 

measurement  of  shore-lines 412, 414, 417, 418, 4! 9 

Stoppani,  A.,  cited 271 

Strachey,  Richard,  cited 2S4 

Stream  Cliff,  compared  with  other  cliflfs 75,  77 


Page. 
Stream  terraces,  compared  with  other  terraces 79.84 

claaaiticatinn  8U 

Sub-Appenine  fauna  397,399 

Subaciiumus  ridge  43 

Submergence,  effect  on  shores 72 

Sulphur  Springs,  mea«uroment  of  8horc-lino.366, 408, 415, 418 

Superior  Lake,  bay  bars 51 

Survoy  of  the  Rocky  ilounlaiii  Region,  fiehl  work  on 

Lake  Ilonuevilh) ]8 

gauging  Great  Salt  Lake     230,409 

Survey  of  the  Territories,  Neocene  lake  beds 99 

Surveys  West  of  the  lOOth  Miaidiaii,  investigation 

of  Lake  Bonneville    17 

map  of  Rush  Lake 228 

measurement  (»f  Hhoreline  362,414 

Synchronism  of  Bonneville  shore-line 309 

Tabernacle  crater  and  lava  6eld,  map 328 

view ^ 328 

description 329 

Talmage,  J.  E.,  analyses  of  water    of  Great    Salt 

Lake 252,  253 

Taramelli,  cited  271 

Tavaputs  Plateau,  volume 390 

Taylor,  volume  of  Mount 390 

Teconia,  height  of  Bonneville  shore-line 365 

measurement  of  height 411,412,  417 

Temperature,  secular  curves  for  Great  Basin 246 

and  humidity .  265 

relation  to  glaciation  276,  283 

relation  to  growth  of  mollusks 300 

Temperatures  of  fumaroles 333 

Temperatures  of  hot  springs 333 

Terrace  Crater 322 

Terrace  Mountain,  spits  of  Bonneville  shore-line 108 

Provo  embankment  series 131, 133 

shore-lino  measureuieuts 372 

Terraces,  north  end  of  Ofiuirrh  Range,  view i 

wave-cut 35 

cut  and-huilt 36,40 

wave-built    55 

classification 78 

comparison 84 

of  disputed  origin 95 

of  Provo  shoreline 127, 128 

Tertiary.    See  a.\so  Keoccne  and  Pliocene. 

Tertiary  beds.  Red  Rock  Pass   173 

Tertiary  lakes  98 

Texas,  interior  basin 11 

Thermos  Springs,  measurement  of  heights 408,415,417 

Thompsou,  Gilbert,  contributions  toEonnevillemap.  126 

map  of  embankments  near  Dove  Creek 138 

discovery  of  outlet. 173 

cited  on  Bear  River  drainage 219 

map  of  mouths  of  Little  and  Dry  Cottonwood 

Canyons :!46 

Thomson,  AViUiam,  cited  on  elasticity 381 

coetticient  of  diffusion 42G 

Tidal  shores 28 

Time  ratios 159,260 

Tintic  Valley  Bay 104 

Tooele  Valley,  ancient  shore-lines 14 

Provo  embankment  series 131, 132 

fault  scarps 353 


INDEX. 


437 


Page. 

Tooele  Valley,  diaatropbism 367 

(See  alao  Grantsville  and  Pass  between  Tooele  and 
Rash  Valleys. 

Tooele-Rusb  Bay 104 

Topograpliic  features  of  lake  shores,  described 23 

distribution 6 

discriujinated 74 

Titpnnirnpbic  interpretation  of  lake  oscillationa 262 

Toronto  Harbor,  structure  of  peninsula 5-i 

map 54 

Towiia  on  site  of  Lake  Bonucvillo lOG 

Trans-Pecips  interior  basin 11 

Transportation,  littoral 37 

Traverse  Range,  fault  scarp 346 

Trees  uf  Great  Basin 9 

Trrsca,  flow  of  solids 383 

Triaugulation,  heights  measured  by 406 

Trowbriujie,  E,  R.,  general  assistant 18 

Tuilla  Valley.     See  Tooele  Valley. 

Tufa,  near  Pyramid  Lake 33 

of  old  shorelines 167 

not  found  in  Cache  Valley 179 

on  Tabernacle  lava  bed 330 

Tuff.Pavant  Butio 326,329 

TaberiLtrlo  Butte 329 

Twin  Peaks,  measurement  of  shore-line 408,415,417 

Tyudall,  John,  cited 284 

Uiakaret  Mduutains  Pleistocene  eruptions 337 

Uuconfoimityof  White  Marl  on  Yellow  Clay.  190, 192, 194, 197 

Undercutting 15L 

Underscore 130,132 

U:;clertow.  origin 30 

function 33,  38 

pulsation 33 

Uphaui,  Warren,  cited  272 

Upper  River  Bed.  section 194 

geologic  map 191 

Utah  Lake  water,  precipitation  experiments. 206 

analysis 207,254 

Utah  Valley,  fault  scarps 343 

Valleys  of  Bonneville  Basin 91 

Valleys  of  Great  Basin  6 

Viisey,  George,  identification  of  fossil  plant 210 

V-b:ira,  description    57 

outlines 58 

of  Bonne villu  shore-lino 108 

interpretation   121 

Vegetation  of  Great  Basin , 9 

Vertebrate  faunas,  compared 397 

Vertebrate  fossils  and  Bonneville  climale ..'...  303 

Volcanic  district  near  Fillmore,  map 320 

Volcanic  epoch  nut  clos-jd 339 

Volcanic  formation  of  Bonneville  Basin 319 

Walled  lakes 71 

Walling,  H.  F.,  theory  of  joint  structure 213 

Warm  Spring  Lake 300 

Wasatch  glaciers  and  Lake  Bonneville 305,306 

Wasatch  Range,  fault  scarps 342 

loading  and  displacement 357 

now  growing 359 

volume 389 


Water  analy  sea 

Water  of  Great  Salt  Lake 

Water  of  Lake  Bonneville 

Water  of  Sevier  Lake 

Wave-built  terrace,  described 

compared  with  other  terraces 

Wave-cut  terrace,  described 

compared  with  other  terraces 

Waves,  shore-forming  agents 

theory  of 

refraction 

function  in  littoral  tiansixutation 

fetch 

function  in  building  embankments 

fetch,  on  Lake  Ontario    

Webster,  Albert  L.,  computation. 

survey  of  Escalaute  Bay 

map  of  shore  features  at  Wellsvillo 

compilation  of  gauge  data    

map  of  Fillmore  volcanic  district 

barometric  work  and  compilation  of  altitudes. .. 

appendix  on  altitudes 

Weber  River,  deltas 

change  of  drainage 

fault  scarps 

Wells ville.  view  of  terraces /. . 

discrepant  shoie  records 

embankments 137^ 

map  and  view  of  ombaukments 

measurement  of  heights 372, 

Wheeler,  George  M.,  position  of  Sevier  Lake  

Wheeler,  H.  A.,  survey  of  Tintic  V;illey  Bay 

map  of  embankments  near  Grantsville  

map  of  Snowplow 

map  of  pass  between  Tooele  and  Rush  Valleys. . 

map  of  Fillmore  volcanic  district  

Wheeler  survey,  investigation  of  Lake  Bonneville.. 

map  of  Rush  Lake 

measurement  of  shoreline   

White,  C.  A.,  explanation  of  lake  ramparts 

White  Marl,  character  ami  distribution 

upper  River  Bed  section 

cause  of  whiteness 

analyses 

over  lava 

White  Mountain,  gypsum 

map  

rhyolite 

height  of  Prove  shore-line 

measurement  of  heights 408,412, 

White  Valley  and  Stausbury  shore-line 

White  Valley  Bay 

Whitney,  J.  D.,  observations  on  ancient  shore-lines 
of  Mono  Basin 

cited  on  cause  of  cstenaion  of  Mono  Lake 

cited  on  climatic  history  of  Great  Basin 

cited  on  synchronism  of  glaciatiun  

cited  on  glaciatum  and  heat 

cited  on  relations  of  Plei-stocene  lakes  and  gla- 
ciers   '. 

Owen's  Valley  earthquake 

Whittlesey,  Charles,  cited  on  subaqueous  ridges 

Willard.  heights  of  shoredines 365, 

measurement  of  heights   412,  413,417, 


Page. 

207,  254 
252 

204 

226 

55 

84 

35 

84 

29 

29 

30 

27 

43, 107 

46, -17 

53 

110 

126.  370 

138 

232,409 

320 

365 

405 

164,  349 

218 

349 

98 

124 

139,143 

138 


412,419 
224 
126 
134 
138 
138 
320 
17 
228 

362, 414 
71 
190 
195 
200 
201 

328,  334 
223 
320 
338 
370 

415,  418 
186 
104 

16 

266 
266 
270 
284 

314 

3G2 

43,44 

370.  372 
418,419 


438 


INDEX. 


Willow  Springs,  hook  near 145 

\V  iiiii  waves,  theory 29 

Winds,  Pleistoccno 332 

Woir,  fossil 303,394,400 

Wocidwanl,  R.  S.,  on  tho  deformation  of  the  gcoid 
by  tlie  removal,  tliroiigli  evaporution,  of  the 

water  of  Lake  liouni-ville 377,421 

on  the  elevation  of  the  surface  of  tho  r.onni-villn 

Basin  by  expansion  due  t"  change  of  rli mate.  .'I7H,  425 


Papo. 

Wi.oilwanl,  R.  W..  analysis  of  tufa 168 

Wright,  O.  Frederiek,  cited 274 

VVright,  George  M.,  field  work 18 

observation  of  oolitic  sand 169 

Yellow  Clay,  charatter  and  dialribntion 100 

upper  Jviver  Bed  section 194 

analyses 2U1 

Young,  Williaid,  riled  173 


V 


